GA8TER01 , KROPODA. 51 



The Argonauta vitrea of authors, Favanne, vii, c, 2; Martini, 1, 

 xiii, 163, must be the shell of a large Carinariu, but the animal is not 

 yet known. 



ATLANTA, Lesueur *. 



Tin- Atluntae of Lcsueur, according to the recent observations of M. 

 Rang, are animals of this onh-r, the >h.-ll of whieh, instead of heing 

 well opened like that of a Cariiwriu, 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 L:imanon thought he had discovered the original 

 Cornu Ammonisf Atlanta Peronii and Mlnntu Keraudrenii, 

 Lesueur, Journ. dc Phys., Ixxxv, Novemb. 1817; and Rang, 

 Mem. de la Soc. d'Hist. Nat., tome III, p. 373, and pi. ix. 



FIROLA, Per on. 



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 (Mid of the tail is frequently observed to proceed a long articu- 

 lat< -d iill-'t, which Forskahl took for a Tacnia, and whose nature is not 

 yet very clearly ascertained. 



One species, the Peterotrac/tea 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, where the body, instead 

 rminating in a compressed tail, is abruptly truncated behind the 

 visceral bundle, Ib. p. 37. 



To these two, now well known genera, I presume we must add, 

 when better understood, the 



TI.MORIENNA, Quoy and Gaym. 



Voy. de Freycln., Zool. pi. Ixxxvii, f. 1, which appears to be a Firola 

 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 

 ( V.rinaria, but is without a foot, distinct bundle of viscera, and 

 shell. 



W6 must not confound the Atlattta of Lesueur with the Atlas described by him in 

 the same place, and which, so confused is his description, I do not know how to 

 claw. 



f Voyage de Lapeyronse, IV, p. 134, and pi. f>3, f. 1 4. 



* FlroUt BKrfico. F. ffibtK*a;F. Forskuka; F. Cu>ra, which is the P/m- 

 trachea corona/a, Forsk. ; F. Frcdcrica, copied Malacol. llluinv., pi. xlvii, f. 4 ; 

 /'. /Vmnw. Add, Ptcrotrachea rvfa, Quoy and Gaym., Voy. dc Freycia., Zool. 



f Ffrotofcte Demarfstia ; Fir. Blammltena ;Fir. rata/a, Less. 

 II We must not confound them with the Monophone of M, Bory Saint- Vincent, 

 (Voy. aux Isles d'Afr.,) which are Pyrosoma-. 



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