they terminate. There is doubt less a general system in even the errors of nature, as is abundantly evinced by the regular series of monstrosity exhibited both in animals and vegetables. It has happened in my professional capacity, that I have had to extirpate a supernumerary thumb from each of the hands of two girls, who were both ideots, though the families to whom they belonged were unknown to each other. 1 have seen many instances of supernumerary thumbs and supernurary fingers in persons to whom the singularity was not hereditary, and I have read of many others; but whether of my own experience, or of authentic record, the redundancy has been on the outer side of the little finger, and outer side of the thumb, never on the back or inside of the hand, or on the sides of the intermediate fingers: and in similar cases as to the toes, the rule has been invariably the same. In the Sacred Writings an example of this kind is given, II Samuel, ch. xxi. ver. 20. "And there was yet a battle in Gath, where was a man of great stature, that had on every hand six fingers, and on every foot six toes, fourand-twenty in number; and he also was born to the giant." The same account is repeated in 1 Chronicles, ch. xx. ver. 6. In the Elementa Physiologia of Baron Haller, numerous examples of this deformity are cited from various authors, with some instances of their hereditary descent, and others of a cutaneous junction between the extra limbs and the next adjoining. That local resemblances, such as those of external parts, the hands, 1 the feet, the nose, the ears, and the eye-brows, are hereditary, is well known; and it is almost equally evident, that some parts of the internal structure are in like manner transmitted by propagation: we frequently see a family form of the legs and joints, which gives a peculiar gait, and a family character of the shoulders, both of which are derived from an hereditary similarity in the skeletons. Family voices are also very common, and are ascribable to a similar cause. parently many of our English surApnames have been taken from the hereditary peculiarities of families, and the same practice existed among the Romans. Pliny, in his eleventh book, chap. xliii. relates an instance · of a Roman poet, named Volcatius, who had six fingers on each hand, and received the surname of Sedigitus in consequence. He also states, that two daughters of a noble Roman, named M. Curiatius, had each six fingers, and that they took. the surname of Sedigita. Persons who had the surname of Flaccus were so called from their pendulous ears; and numerous other instances are recorded by classic writers of surnames being derived from family marks. Anatomical researches have not been so generally extended as to determine the prevalence of internal peculiarities, and perhaps they do not reach to the sanguineous system. I have known two instances, in two different families, of the high division of the brachial arteries having the ulnar branch placed above the fascia of the biceps muscle at the inner bend of the elbows, and yet the father, the mother, the brothers and sisters of those two persons were not so de formed. formed. Those marks called nævi waterni, which are derangements of the sanguineous vessels, are not hereditary, whilst less remarkable changes in the ordinary skin are often so I have lately seen a man, and who is now living, who has a small pendulous fold attached to the skin of his upper eyelid, and the same peculiarity has been transmitted to his four children. It would have been interesting to know, whether any similarity of structure existed in the families of the two rare examples of a total transposition of the abdominal and geny uncertainly variegated. The Your much obliged and ANTHONY CARLISLE, Bart. K. B. P.R.S. &c. thoracic viscera. (Phil. Trans. for To the Right Hon. Sir J. Banks, OF TENERIFfe. From Memoirs of the Geological In particular breeds of animals, SOME ACCOUNT OF THE ISLAND the characteristic signs are generally continued, whether they be long to the horns of kine, the fleeces of sheep, the proportions of horses, the extensive varieties of dogs, or the ears of swine. In China the varieties of gold and silver fishes are carefully propagated, and with us, what are vulgarly called "fancy pigeons" are bred into most whimsical deviations from their parent stock. As wild animals and plants are not liable to the same variations, and as all the variations seem to increase with the degree of artificial restraint imposed, and as certain animals become adapted by extraordinary changes to extraordinary conditions, it may still be expected that some leading fact will eventually furnish a clue, by which organic varieties may be better explained. A few generations of wild rabbits, or of pheasants under the influence of confinement, break their natural colours, and leave the fur and feathers of their future pro [By the Hon. Henry_Grey Bennett, M. P. F. R. S. President,] The island of Teneriffe is the principal island of the seven in the The island narrows at its northeastern and widens considerably at its south-western extremity. About the centre of the latter, or perhaps to describe more accurately, to the westward of the central point, is the mountain called by the Spaniards el Pico di Tiede, but better known .by by the name of the Peak of Teneriffe, and which is the highest land not only in the island, but in all the Canaries; the mean of various observations making it 12,500 feet above the level of the sea. It is visible at a great distance; we saw it perfectly distinct 34 leagues off by chronometrical observation, when it appeared rising like a cone from the bed of the ocean; and I have heard that it has been clearly distinguished at a distance of fortyfive leagues. The rocks and strata of the Island of Teneriffe are wholly vol canic; a long chain of mountains, which may be termed the central chain, traverses the island from the foot of the second region of the Peak sloping down on the eastern, western, and northern sides, to the sea. Towards the south, or more properly the S.S.W. the mountains are nearly perpendicular, and, though broken into ridges and occasionally separated by deep ravines that are cut transversely as well as longitudinally, there are none of those plains nor that gradual declination of strata that the south-eastern and north-western sides of the island exhibit. From the Barranco Seco, in the neighbourhood of Santa Cruz, to the northerly point called Punta del Hidalgo, a series of steep and abrupt mountains form headlands to the sea, separated from the central chain by the valley of Laguna; these mountains are rugged and peaked, drawn up, if the term may be used, in a column, and are di vided by deep ravines. The sides of these mountains are steep, being in many places cut nearly perpendicular to the horizon, and are all composed of lava generally of the basaltic formation, mixed with beds of of a few leagues I counted no less than seven cones of extinct volcanoes, and the country is covered with scoria, exhibiting no appearance of culture, and hardly any of vegetation; it is more broken into ravines and more intersected by lava torrents than on any of the other sides of the island. Numerous peaked and conical mountains rise upon the slope of the chain, and the whole country is covered by scoria, and is one continued stream of lava. The Montana Roxa itself is a singular example of the dislocation of strata so commonly found in countries of volcanic formation; it is evidently a slip or fall of semi-columnar lava, and slopes into the sea at an highly inolined angle. The ordinary strata of the island are as follows, reckoning from below upwards: 1st. the porphyritic lava covered by scoria and sometimes by pumice. This lava is composed of hornblende and feldspar, and contains no other substance. The next stratum graduates into what the Spaniards call Roccaverde or greenstone, and is composed of feldspar and hornblende; upon this is generally a thick stratum of pumice, and last of all towards the surface is the basaltic lava covered also by tufa and ash. This lava decomposes the soonest. It also contains the greatest variety of extraneous substances, and is sometimes divided by a layer of large crystals of olivine some inches long, and towards the northeast is often intersected by strata of porphyritic slate. These lavas are more earthy and cellular than those which I have had an opportunity of observing elsewhere, yet they contain fewer extraneous sub stances than those of Ætna and Vesuvius; they are in some places exposed to view in the vallies similar to those of the Corral in the island of Madeira. The valley of Las Guanchas on the north-west side of the Peak, contains, according to M. Escolar, above 100 strata of lava, the one reposing upon the other, at times alternating with pumice and tufa. The depth of these strata varies. M. Escolar has seen one of basaltic lava between 100 and 150 feet in depth in one solid mass, cellular at the surface, but gradually becoming more compact towards the bottom. This basaltic lava contains olivine and hornblende, and in the caves on the coast, zeolite. This substance is also found in stalactites and in masses, sometimes in layers spread between the strata and diffused over the rock. Nodules of chalcedony are some times also found, but these substances occur only in the chain of mountains towards the north-east, from the northern extremity of Santa Cruz to the point of Hidalgo. The lavas of the island are of an endless variety, and the number of streams that have flowed are much beyond all enumeration. The whole surface is either ash, or solid or decomposed lava, which seems again and again to have been perforated by volcanic eruptions; the number of small extinct volcanoes is prodigious, they are to be found in all parts of the island, but the stream that has flowed from even the largest of them, such as the lava of the Peak called el Mal Pais, is trifling in comparison with that immense mass of lava mountains which constitute the central chain of the island, and which stretch out as as headlands like those of las Hor- all volcanic, and one has a visible cas and San Ursula. I never found in situ those masses of columnar basaltic rock that are so common in the island of Madeira: but in the valley of las Esperanzas, in the chain of hills to the north-eastward of the town of Santa Cruz, they lie scattered about in considerable numbers, and M. Escolar told me that he had seen strata of them to a considerable extent, exhibiting with precision the columnar basaltic form; the modern lavas of the Peak are all basaltic; that of 1704 is decidedly so, as well as that of 1798, though not exhibiting any prismatic form.Prisms of basaltic lava are yet found on the peak: I picked up one, though there are no strata of them to be met with. The metals are rare, and afford but little variety; specular and micaceous iron, black and grey manganese, are all that have hitherto been discovered. The salts that are so common on Vesuvius, are here seldom met with. Augite is also rare, and mica and leucite, though carefully sought after, have hitherto not been found. In that part of the island between Laguna and Tacaronte, where there are few streams of lava, the soil is evidently volcanic. I examined many of the clods that were turned up by the plow, and found them all alike they contained much strong clay, with crystals of feldspar, olivine, and specular iron.Dr. Gillan, who accompanied Mr. Barrow and Sir G. Staunton, has advanced an opinion, that between Laguna and Matanzos there are no signs of volcanic formation. That the currents of lava occur but seldom is most true; but the mounaius in the vicinity of Laguna are crater; besides, the assertion would prove too much; for it would go to maintain that the Campagna Felice, as well as the plains of Catania, were not created by the ash and pumice eruption of Vesuvius and ina. The bed of soil is here very deep. I examined some ravines that the rain had laid open to the depth of 30 or 40 feet: the strata were indurated at the bottom, and resembled the tufa in the vicinity of Naples, and all contained the substances mentioned above.— This tufaceous character. changes as you ascend the hill that separates Laguna from Santa Cruz; the bill itself, and the whole neighbourhood of the latter city, is one continued stream of lava, hardly at all decomposed, with little or no vegetation; but here and there in the hollows some few stunted plants of the aloe algarvensis, and the cytisus. Having given a general account of the island, I shall now attempt to describe the country of the Peak, which mountain I ascended on the 16th of September, 1810. The road from Puerto Orotava to the city of Orotava, is a gradual and easy slope for three or four miles, through a highly cultivated country. The soil is composed of volcanic ash and earth, and to the eastward of the town of Puerto di Orotava are the remains of a recent volcano, the crater and cone being distinctly visible. Leaving the town of Oratava, after a steep ascent of about an hour through a deep ravine, we quitted the culti vated part of the slope or valley, and entered into a forest of chesnuts; the trees are here of a large size. This forest of chesnuts is mixed with the erica arborea, or trce |