110 CLASS III. GASTEROPODA. ORDER VI. PULMOBRANCHIATA. 
gitudine superante, basi integra ; marginibus superné disjunctis, 
labro tenui, simplici; columella subsolida, acuté plicata. 
The genus Chilina, proposed by Gray for the reception of an interesting 
series of pulmoniferous mollusks inhabiting the La Plata and other rivers 
of South America, affords us an instance in which we may safely appre- 
ciate the labours of this skilful imitator of De Montford. The first spe- 
cies with which naturalists were acquainted was discovered by Dombey ; 
it was assigned by Bruguiére to Bulimus, but Lamarck referred it to 
Conovulus (Melampus), a genus which he afterwards united to Auricula. 
The Chilinz constitute a group of considerable importance in the series, 
because they are exactly intermediate in their organization, as well as 
in their habits, between the two families of the Auriculacea and the 
Lymneana, partaking equally of the characters of both. Deshayes and 
D’Orbigny are of opinion that the Chiline are more nearly allied to 
the latter ; we have, however, followed the arrangement of Gray, in con- 
sequence of the plait on the columella being a strong and unerring cha- 
racter. 
The shell of Chilina may be described as being thin, ovate or ovately 
oblong, covered with a green, spotted epidermis, and having a rather 
acute spire, though sometimes a little depressed; the aperture is oval, 
longer than it is wide, and entire at the base; the margins are superiorly 
disjoined, and the lip is thin and simple; the columella is rather solid, 
and sharply plaited. 
Ewamples. 
Pl. CLXXXIX. Fig. 1. 
CuILina Ropustior, Sowerby, Malac. and Conch. Mag., part 2. Sow- 
erby, Jun., Conch. Illus. 
Pl. CLXXXIX. Fig. 2. 
Cuitina FLuctruosa, Gray, Spicilegia Zoologica, pl. 6. f.19. D’Orbigny, 
Voyage dans l’Amérique Méridionale, Mollusques, p. 334. pl. 43. 
f. 13.to 16. 
Otis fluctuosa, Humphreys. 
