78 Lamarck’s Genera of Shells. 
Shell composed of two testaceous, small, crescent-shaped 
valves, separate, and adhering near the lateral aperture. 
Type. Otion Curieri*. (Lepas aurita. Linn.) 
Body and horns without spots. South Seas. Pl. ui. Fig. 17. 
2 Species. 
CLASS XI. 
CONCHIFERA*. 
Animals soft, inarticulate, always fixed in a bivalve shell ; 
without head or eyes; mouth naked, concealed, not furnished 
with any hard parts; the whole body covered with a large 
mantle, forming two lamellar lobes ; lamina often free, some- 
times united before. Generation oviparous, without copula- 
tion. 
Branchie external, situated on both sides, between the body 
and the mantle. Circulation simple ; heart with only one ven- 
tricle. Some ganglia, various nerves, but no ganglionated me- 
dullary cord. 
Shell always bivalve, wholly or partly covering the animal, 
sometimes free, sometimes fixed; the valves generally uniteds 
on one side by a hinge, or a ligament. Shell sometimes in- 
creased by accessary testaceous pieces, not belonging to the 
valves. 
Linneus arranged all animals, without skeletons and articu- 
lated feet, in one enormous class, vermes, which he divided into 
five sections, viz., intestina, mollusca, testacea, lythophyta, and 
zoophyta. His mollusca, as a section of the vermes, compre- 
hended some true mollusca, all the radiaria, some annulata, and 
cirripeda, whilst other true mollusca were separated from them, 
because they have ashell. This bad arrangement still exists in 
the Systema Nature. 
The two valves of a conchiferum are sometimes unequal, when 
the shell is said to be inequivalve ; sometimes exactly alike in 
their general form and size, when it is called an equivalve shell. 
The ligament of the valves is sometimes external, sometimes 
* Cuvier’s. + Concha, and fero, bearing shells with two valves. 
