126 COBDirOEM. 



two or three recent species are known, resembles many species 

 of Venus and Cytlierea in general form ; but differs in having 

 lateral teeth, and in the paileal impressions, which in all the 

 Veneres, &c. is sinuated. From Lucina it may be known, not 

 only by its oval form, but also by the muscular impressions, 

 which, in Lucina, are produced into an elongated point ; it will 

 also be distinguished from Tellina, by the want of a posterior 

 fold in the valve, for which that genus is remarkable. C. Fim- 

 briata is an inhabitant of the Indian Ocean. Several fossil 

 species are found in the recent formations, above the chalk, at 

 Grrignoa and Hautville. PL v. fig. 101. 



COEBULA-. Bruguiere, 1792. (A little basket.) Fam. Cor- 

 bulacea, Lam. Conchacea, ~S[.--Descr. Inequivalve, sub-equi- 

 lateral, transverse, gibbose, not gaping ; cardinal tooth in each 

 valve, conical, curved, prominent, inserting its extremity into a 

 pit in the opposite hinge ; cartUage attached to the tooth of the 

 smaller valve, and the pit in the larger ; muscular impressions, 

 two in each valve, distant, rather irregular ; paileal impression 

 posteriorly angulated. Obs. The shells composing this genus 

 were placed in My a by Linnaeus, but differ from the true Myse 

 in having a sinus in the paileal impression, and a prominent 

 Hgamentiferous tooth in each valve, whereas the My as have but 

 one. The Corbulse are marine, some species inhabiting the 

 British coasts. Fossil species occur abundantly in green sand, 

 London clay, crag, and corresponding formations. C. Nucleus. 

 PL iv. fig. 89. 



CORBULACEA. (Corbulees, Lam.) A family of the order Con- 

 chifera Dimyaria, Lam., containing the genera — 



1. CoRBULA, with a prominent curved tooth. The Fresh- 



water species has been separated under the name Pota- 

 momya. Fig. 89. 



2. Pandoba. Thin, pearly, no teeth. Fig. 90. 

 COE.DIFOEM, {Cor, a heart.) Heart-shaped, a term applied 



generally to any shell which may be fancied to resemble a heart 

 in shape, as Isocardia, fig. 126, and Cardium Dionseum, fig, 

 122. 



