774 CLASS XIII. 
GEGENBAUER I. L. s. 210.] 
According to CANTRAINE it does not differ from the preceding genus, the 
shell is cloven at the sides as in Hyalea, 1. 1. p. 23. 
Add genus Lurybia Rane Ann. des Sc. nat. X11. 328. 
Creseis Rana. Shell subulate, furnished with an orbicular 
opening anteriorly, not cloven at the sides. Mantle not produced 
at the sides. 
Comp. Rane Ann. des Sc. nat. XII. pp. 305—318. 
Note.—Here also or with the preceding genus is to be placed : 
Sub-genus Cuvieria Rane. See Ann. des Sc. nat. XII. p. 322, Pl. 45 B, 
figs. 1—8, V. BENEDEN 1. 1. Pl. 4 B. 
Spiratella BLAINV., Limacina Cuv. Body anteriorly auriculate 
on both sides with a triangular pinna, posteriorly convolute. Shell 
fragile, discoidal, on one side deeply umbilicate, on the other with a 
spire slightly exsert. 
Sp. Spiratella arctica nob., Linc cina helicinalis Lam., Buatnv. Malac. Pl. 
48 bis, fig. 5, V. b EH . 60 Sur la Limacina arctica, Mém. de VAc. 
royale de Brux. Tom. xtv. 1841, Pl. 5. This little animal is very numerous 
in the North Polar Sea, and serves the whale for food ; see O. FABRICIUS 
Faun. Grenl. pp. 387—389, by which writer it is named Argonauta are- 
tica. In PHipps’s Voyage towards the N. Pole it is noticed under the name 
of Clio helicina, and it is probable that CuviER intended to name it Helt- 
cina, a name which we should prefer to that of Zimacina which perhaps 
originated merely in a mistake. 
Cymbulia Péron. Animal included in shell, except two large 
pinne, confluent [partially, with a middle lobe that represents the 
foot. GEGENB.]. Two contractile tentacles in front of mouth. 
Shell hyaline, elongate, cymbiform, truncated posteriorly. 
Sp. Cymb. Peronii Cuv., Péron Ann. du Mus. xv. Pl. 3, pp. 1o—12, GUERIN 
Iconogr., Moll. Pl. 4, fig. 2, V. Bennepen Mém. de Acad. de Bruw, xii. 
Pl. 1; Mediter. Sea; according to CANTRAINE these animals often lose their 
shell. [The shell is formed within the mantle, and normally is covered by 
a thin lamella of the same. This last is easily torn and thus perfect speci- 
mens are rare: hence also the ease with which the animal loses its shell. 
The shell has the consistence of soft cartilage and contains chitin. GEGEN- 
BAUER l. 1. pp. 41, 42.] 
[ Tiedemannia DELLE CHIAJE. Pinne conjoined with the foot 
to form an orbicular disc. Mouth at the apex of a long proboscis, 
very often bent backwards. Shell hyaline, gelatinous, slightly 
excavated. 
