tance from their termination. The belly of the shell is wholly covered with a brilliant, white callosity, formed by the deposit of vitreous matter.

Length fourteen-twentieths, breadth nine-twentieths of

an inch.

Inhabits the southern coasts of the Gulf of Mexico. In the Cabinet of the Boston Society of Natural History, that of D. H. Storer, M. D., and my own collection.

The shell bearing most resemblance to it is the M. bivaricosa; but in addition to the spire of that species being much more prominent, the folds on the columella, have all nearly the same direction, the margin is double and its edges rounded; whereas, in this, the two upper folds are nearly transverse, the two lower very oblique, and the edges of the margin very sharply defined. It is also much broader in proportion to its length than the M. bivaricosa. The most unpractised eye could not fail to detect a difference instantaneously, between the two shells. In both the specimens in my possession, the characters above inentioned are uniform.

It is far from my intention to indulge in the too prevalent system of constituting new species from mere varieties of a shell; but while we have such authority as Lamarck and Kiener for considering the M. faba and M. bifasciata, the M. formicula and M. muscària, the M. glabella and M. aurantia as being each distinct species; where the closest scrutiny can detect no other differences than those of size and coloration; the shell under consideration must be acknowledged to possess far stronger claims to a name of its own.

It can hardly be doubted, that had any of the European naturalists met with it, they would have designated it as a new species; and after the fiat of their approba

tion, there is as little question it would have been received as such by us. There is no reason why we should not adopt a similar course on this side the water.

Our situation is peculiarly favorable for the procuring of new objects of Natural History. The researches of a large portion of our community, are daily extended into new regions, abounding with such objects. We have, doubtless, in our several collections, many specimens yet undescribed; and why should we, through indolence or timidity, defer making them known, till at last some one abroad, as fortunate and less hesitating than ourselves, does so, and deprives us of the opportunity of casting our mite into the great treasury of Natural History?

I have been led to these remarks, by the fact of there having been for a long time, in my own limited cabinet, a number of shells, which have only very recently been described, and of which I should have long since given descriptions myself, but for the cautious prudence of some of my friends, and the cry of "oh there is no doubt it has been described by somebody already." So far as in my power, I am determined to prevent such mortifications in future, by describing at once, whatever there may be good and sufficient grounds for believing new objects.

The shell before the Society belongs to the third group of MARGINELLE according to Kiener's arrangement, having the spire, wholly or partially concealed by a vitreous deposit.

I do myself a pleasure in naming this shell after my friend D. Humphreys Storer, M. D., whose ardent love of Natural Science, and devotion to its advancement among us, are too well known, to require this feeble tribute as any thing more than a token of my own personal sense

of indebtedness to him, in laboring to present the public with a faithful translation of Kiener's Iconography of Recent Shells.

ART. XXII.-ANATOMICAL DESCRIPTION OF THE GALAPAGOS TORTOISE. BY J. B. S. JACKSON, M. D. Read February 1st, 1837.

In the summer of 1834, Capt. John Downes, of the United States Navy, soon after he returned from his voyage in the frigate Potomac, made a very valuable present to this Society of two large Land Tortoises. They were the largest and finest specimens out of a number brought by him from the Galapagos Islands, a small volcanic group in the Pacific Ocean, lying under the equator and about 110 leagues distant from the South American coast. One of them, which was a male, died in the course of the summer; the other, a female, lived till the weather became cold, was kept in a frozen condition through the winter, and dissected in the following spring. Both of the dissections were hastily made, but notes of each were taken at the time; and these, imperfect as they are, with a few additions which I can safely make, I would now offer to the Society.

The only scientific description which I have seen of this Tortoise, is by Dr. Harlan and may be found in the 5th Vol. of the Journal of the Academy of Natural Sciences of Philadelphia. The specific name elephantopus, which he has given it, is very appropriate, and is founded on a resemblance which has been noticed by other observers. He considers it as quite distinct from

the TESTUDO Indica and that there is no other species with which it can be confounded. Dr. Bell, however, the author of a very splendid work on the TESTUDINATA, now in the course of publication in London, regards the two as the same species;-that it is indigenous to the Galapagos Islands, and has been casually introduced into other countries through the medium of commerce. This difference of opinion may be accounted for by the remark which has been made, that entirely distinct species are found in this group of islands.

Captains Porter, Delano, Basil Hall, and more recently Mr. J. N. Reynolds, have each in their popular Journals, given an interesting description of these tortoises of the profusion in which they are found, such as to have furnished a name for these islands to the Spaniards who discovered them (galapago, a fresh-water tortoise)-of their immense size, some of them weighing between 3 and 400 pounds-their being able to live without food or water for a year or more, their harmless disposition, their ungainly and even disgusting appearance, their clumsy movements and their great delicacy as an article of food, far exceeding, according to Capt. Porter, the finest green turtle. The following additional account of their habits was prepared for the Society by Mr. Reynolds, the author of the "Voyage of the Potomac," a gentleman to whom the Society is indebted for many valuable donations, and at whose suggestion Capt. Downes was induced to present to us the two fine specimens which are the subject of this paper. He says, "From the last of May to December, embracing the rainy season, the Terapin leaves the mountains and high grounds and may be found spread in all directions over the plains and low grounds near the sea, where they feed principally upon the prickly pear, and

find water in the little lakes in the crevices of rocks. From January to May, as the dry season advances, they return again to the high ground where the trees are larger, vegetation more abundant and where springs may be found issuing from the sides of the mountains. These watering places become much frequented, and paths leading to them may be traced for a great distance along the sides of the hills; and I have seen in many places, the rocks worn away more than six feet in depth, and just sufficiently wide to allow them room to pass. At these springs hundreds of them are often seen at a time, waiting their turns to drink, or, becoming impatient, pile themselves one upon another, in their efforts to obtain water. When satisfied, they again return by the little roads hewn through the soft rocks and again disappear amid the thick underwood."

The following observations were made on our own specimens.

External characters.-The male tortoise weighed at the time of its death 302 lbs., having gained 17 lbs. during the few weeks that it was in the possession of the Society. The general outline and the form and number of the scuta are so well represented in Plate XI., as scarcely to need any description; of the vertebral there are five, of the costal four on each side, of the marginal twenty-three and of the sternal sixteen. A remarkable concavity of the sternum, which belongs to the sex, could not be well represented, neither the slight depth of the furrows between the scuta which in some places are so faint as to be with difficulty traced. Surface of the upper shell quite smooth, except near the edges of the scuta, where are seen the remains of the concentric lines, and of the lines which radiate from the angles of