Natural-Historical Collections. 455 
form of the shell well distinguishes it. I have not succeeded in obtaining a 
second individual. 
The Atlantides are extremely common, especially the Aélantis of Peron, which 
is smaller in the Mediterranean than in the Ocean, and still more so than in the 
Indian Sea. I have with great pleasure observed the Adlantis of Keraudren, 
and its animal, which is by much the prettiest molluscous animal that 1 know. 
I have obtained from it some new particulars with respect to this genus, which 
it will be well to add to what I have already said of it in an anatomical memoir, 
published two years ago, in the collection of the Natural History Society of 
Paris. I have discovered, for example, that the mouth is armed with a horny 
apparatus, similar to that which is observed in the Carinarieé ; that the posterior 
part of the animal, that which bears the operculum, is a little dilated in the ver- 
tical direction, so as to form a kind of secondary fin; a circumstance which adds 
to the remarkable similarity between the Aélantides and the other Nucleobranche 
tata. I shall also have some particulars to add to those already known respecting 
this interesting genus. 
The Anatifa vitrea has also afforded me an opportunity of making some ob- 
servations, which will contribute to render it better known. It is not fixed, like 
all the other animals of its class, but free and pelagic, floating about in the open 
sea just as much as the Janthina ; for, like it, it suspends itself at the surface of 
the sea by means of a cluster of white and transparent air vesicles. In the Ana- 
tifa vitrea this singular organ is an appendage to the fleshy pedicel. By this 
means the animal floats free upon the water, but it falls to the bottom when it 
pleases. 
On the rocks at Cadiz, I found two beautiful Dorises, which are also unknown. 
to me, and which I have not been able to refer to any of the species in your 
plates ; a fine Pleurobranchiate species, which I had already met with on the 
coasts of Rochelle, and of which the inner testaceous piece presents a very dis= 
tinct summit, with from one to one and a half spiral turns; lastly, the Sigaretus 
of Kindelau, which has been described in the Bulletin of the Linnean Society of 
Bordeaux. I have discovered that the animal of this small shell changes its 
colour three or four times during its life, a circumstance which may easily lead. 
to error by inducing observers to consider as distinct species what are merely vae 
rieties dependent upon age. This is also the case with the Pleurobranchiate 
species, of which I made mention above. 
I am certain that, had we remained longer at Cadiz, I should have made an 
abundant harvest, and this so much the more assuredly, that its shores receive the 
tribute of three different countries. In fact, there are found upon them many- 
mollusca of the Mediterranean, several from the Canary Isles, the Cape Verd 
Isles, and even the West Indies, and, lastly, the greater part of those of the Gulf 
of Gascogny. 
I keep all these animals in spirit of wine, and have previously taken drawings 
and descriptions from them while living. I have done the same with many other 
mollusca, which are well known, but which have either never been figured, or have 
been represented in an imperfect manner, such as several species of living Tere- 
bratule, of which | have especially studied the singular system of their internal 
calcareous framework. I may add, that I have four new species of this genus, 
and that I have described the animal of the Crania from live specimens. 
I shall soon set sail for the western coasts of Africa, where, notwithstanding 
the beautiful discoveries already made by Adanson, I anticipate numerous new 
mollusca and fishes. The taste for natural history is spreading among the offi- 
cers, who are all desirous of having an occupation to destroy the ennui and mo- 
notony of a long campaign. M. Joly, in particular, my first surgeon, who is an 
excellent officer, lends me great assistance. We intend to collect in all the 
branches of natural history, which will, perhaps, enable me to discharge the debt 
I owe to the naturalists of the capital, who have received my investigations with 
indulgence, or who have deigned to honour me with their friendshipp—Bulfet, 
des Sciences Nat. 
