MOLLUSCA. 777 



Pterotrachea FORSK., Firola BRUG., PERON. Body naked, elon- 

 gate, with integument almost pellucid. Two eyes. Tentacles (very 

 often) none. Head with a fleshy proboscis. Branchiae pinnate, 

 free, at the posterior part of back. 



Sp. Pterotrachea coronata FORSK., Icon. rer. nat. Tab. 34, fig. A (copied in 

 Encycl. meth., Vers. PL 88, Firola, fig. i) ; in the Mediterranean. LESEUER 

 has given a monograph of this genus in the Journal of the Philos. Soc. of 

 Philadelphia, of which BLAINVILLE has made use in the article Firola, 

 Dictionn. des Sc. nat. Tom. xvn. pp. 6268. Usually the tentacula are 

 wanting. The species in which they are present were united by D'ORBIGNY 

 under the name of Cerophora. Here belongs Firola caudina RANG, 

 GUERIN Magas. de Zool. 1832, Cl. v. PI. 3, GUERIN Iconogr., Moll. PI. n, 

 fig. 3 [For the Anat. and Hist, of Development, see GEGENB. 1. 1. pp. 

 J 53 185, and HUXLEY 1. 1. on the Anat. of Firolo'ides (Firola) 1. 1. pp. 

 30 36. The auditory vesicle was shewn by LEYDIG Anatortiisch. Bemar- 

 Tcung. ub. Carinaria, Firola und Amphicora Zeitschr. fur wissensch. Zool. 

 m. 1851, p. 328.] 



According to D'ORBIGNY the singular genus Sagitta (see above, p. 246) 

 should be placed here. 



Carinaria. Body elongate. Head with two long, subulate ten- 

 tacles, and two sessile eyes behind the base of tentacles. A small 

 shell at the posterior part of back, thin, pellucid, conical, com- 

 pressed, with apex turned backward. 



These animals have much resemblance to the preceding genus, and 

 CUVIER at first thought that the Pterotrachece described by FORSKAL had 

 only accidentally lost their shell. Memoires, Moll. No. 18, p. 31. They 

 differ, however, by the constant presence of two tentacles in front of the 

 eyes and by small inequalities or tubercles on the skin. 



Sp. Carinaria cymbium (Argonauta Cyrribium L. ?) Ann. des Sc. nat. xvi. 

 PL T, GUERIN Iconogr., Moll. PL u, fig. i, POLI Testae, utr. Sic. in. 

 Tab. 44, figs, i n ; in the Medit. Sea. POLI and DELLE CHIAJE gave an 

 anatomical description of this animal (Test. ill. pp. 26 35, and Memorie 

 Sulla Storia e Notom. degli Anini. s. v.), which was afterwards completed 

 by MILNE EDWARDS as to several remarkable peculiarities, Ann. desSc. nat, 

 sec. Se'r. Tom. 18, Zool. pp. 323329, PL x. fig. 3, PL xi. The remark 

 of LINN.EUS, that the shell is not larger than a grain of sand, does not 

 apply to this species, which therefore has also been often confounded with 

 Carina vitrea, a larger species from the Indian Ocean ; MARTINI, Tab. 1 8, 

 fig. 163, BLAINV. Malac. PL 47, fig. 3 a. 



Atlanta LESUEUR. Head furnished with a proboscis, two cy- 

 lindrical tentacles, and two eyes. Foot compressed, acuminate 

 towards the end, with a suctorial disc in the margin. Thin oper- 

 culum, adhering to the ventral part below the foot. Shell very thin, 

 involute, carinate. 



