352 MOLLUSCA. 



Pterotrachea, Forsk., 

 But we have been compelled to subdivide them. 



Carinaria, Lam.(l) 



The nucleus formed of the heart, liver and organs of generation, 

 covered by a slender, symmetrical shell, the point of which is bent 

 backwards and frequently relieved by a crest, under whose anterior 

 edge float the feathers of the branchiae; two tentacula on the head, 

 and the eyes behind their base. 



One species, Carinaria cymbium, Lam.; Peron, Ann. du Mus., 

 XV, iii, 15; Poli, III, xliv; Ann. des So. Nat., tome XVI, pi. 

 1, inhabits the Mediterranean. 



Another, the Carinaria fragilis, Bory Saint-Vincent, Voy. 

 aux Isles d'Afr., I, vi, 4(2), is found in the Indian Ocean. 

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

 xiii, 163, must be the shell of a large Carinaria, but the animal is 

 not yet known. 



Atlanta, Lesueur(3). 



The Atlantse 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 MoUusca from the Indian Ocean, in 

 one of which Lamanon thought he had discovered the original 

 Cornu Ammonis(4) Atlanta Peronii and Atlanta Keraudrenii, 

 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, 



(1) Forskahl comprised all these animals in his genus Ptehothachea, for which 

 name lirugiere substituted that of Firola. Peron having divided the genus, 

 appropriated the name of Carinaria to those with a shell, and that of Firola to the 

 others. Rondelet gives the Carinaria, but without its shell " De Insect. Zooph. 

 cap. XX." 



(2) Add: Carinaria depressa, Rang, Ann. des Sc. Nat., Feb. 1829, p. 136. 



(3) We must not confound the Mlantw of Lesueur with the Mas described by 

 him in the same place, and which, so confused is his description, I do not knov- 

 how to class. 



(4) Voyage de Lapeyrouse, IV, p. 134, and pi. 63, f. 1 4. 



