GASTEROPODA HETEROPODA, 
61 
The Argonaiita vitrea oi authors, Favanne, vii, c, 2; Martini, I, 
xiii, 163, must he the shell of a large Carinaria, but the animal is not 
yet known. 
Atlanta, Lesueur * * * § . 
The Atlantae of Lesueur, according to the recent observations of M, 
Rang, are animals of this order, the shell of which, instead of being 
well opened like that of a Carinaria, has a narrow cavity, spirally 
convoluted on one plane ; its contour is relieved by a thin crest. 
They are extremely small Mollusca from the Indian Ocean, 
in one of which Lamanon thought he had discovered the orio-inal 
Cornu Ammonisf — Atlanta Peronii and Atlanta K eraiulremi, 
Lesueur, Journ. de Phys., Ixxxv, Novemb. 1817; and Rang, 
Mem. de la Soc. d’Hist. Nat., tome III, p. 373, and pi. ix. 
Firola, Peron. 
The body, tail, foot, branchiae and visceral mass as in the Carinaria, 
but no shell has ever been observed; the snout is elongated into a re- 
curved proboscis, and the eyes are not preceded by tentacula. From 
the end of the tail is frequently observed to proceed a long articu- 
lated fillet, Avhich Forskahl took for a Taenia, and whose nature is not 
yet very clearly ascertained. 
One species, the P eterotrachea coronata, Forsk. ; Peron., 
Ann. du Mus., XV, ii, 8, is very common in the Mediterranean, 
and M. Lesueur describes several from the same sea, which he 
considers as different. — Journ. Acad. Nat. Sc. Philad., Vol. I, 
p. 3, but which require further comparison;!:. 
M. Lesueur distinguishes the Firoloidce, Avhere the body, instead 
of terminating in a compressed tail, is abruptly truncated behind the 
visceral bundle, Ib. p. 37§. 
I'o these two, now well known genera, I presume we must add, 
when better understood, the 
TimoriennAj Quoy and Gaym. 
Voy. de Freycin., Zool. pi. Ixxxvii, f. 1, which appears to be a Fii’ola 
divested of its foot and bundle of viscera ; and the 
Monophora, Id .\\ 
Voy. de Freycin., Zool. pi. Ixxxvii, f. 4, 5, which has nearly the form 
of a Carinaria, but is without a foot, distinct bundle of viscera, and 
shell. 
* We must not confound the Ailantm of Lesueur -w ith the A described by him in 
the same place, and A\hich, so confused is his description, I do not know how to 
class. 
h Voyage de Lapeyrouse, IV, p. 134, and pi. 63, f. 1 — 4. 
X Firola mutica; — F. gibbosa; — F. Forskalea ; — F. Cuviera, which is the Ptero- 
irachea coronata, Forsk. ; — F. Frederica, copied Malacol. Blainv., pi. xlvii, f. 4 ; — 
F. Peronii . — Add, Pterofrachea rvfu, Cluoy and Gaym., Voy. de Freycin., Zool. 
pi. S7, f. 2 and 3. 
§ Firolo'ida Demarestia ; — Fir. Blainvilliana ; — Fir. aculeaia, Less. 
II We must not confound them with the Monophora; of M. Bory Saint- Vincent, 
(Voy. aux Isles d’Afr.,) which are Pyrosomae. 
E 2 
