121 



The genus Iphigenia, Schumacher, is substituted for the genus C'apsa, 

 Lamarck, a name preoccupied by Bruguiere to distinguish the Linnsean 

 Venus deJJorata, which is Lamarck's Sanguinolaria rvgosa. The animal 

 has not been described, and the genus has been separated from Donax 

 more on account of its peculiarity of habit than upon conchological grounds. 

 The Iphigenia are confined to brackish waters, inhabiting, so far as has 

 been observed, the estuaries of Senegal, Brazil, and Central America. The 

 hinge of the shell varies a little from that of Donax in having lateral teeth 

 onlv in one valve, and those often somewhat obsolete. 



Species. 



1. altior, Sow. 3. laevigata, Gmel. 5. ventricosa, Phil. 



2. Brasiliensis, Lam. 4. media, Shutt. 



Figure. 



Iphigenia laevigata. PI. 37. Tig. 202. Shell, exhibiting the inferior 

 of the left valve, with the lateral teeth almost obsolete. 



Genus 3. LUCINA, Bri/guiere. 



Animal ; orbicular, its mantle freely open in front, with the edges 

 plain or fimbriated ; sipko?ial orifices sessile; foot very long, 

 tubular ; branchial leaflets of each side united into one. 



Shell; mostly orbicular, sometimes fiat, sometimes rather gibbous, 

 generally equivalve, moderately inequilateral ; hinge typically 

 composed of two divergent cardinal teeth, and two somewhat 

 distant lateral teeth, noio elongated, now short and produced, in 

 each valve, all of which are sometimes obsolete. 



Under Lucina we have a most variable assemblage of species connected 

 nevertheless by a uniformity of type which renders the genus easy of recog- 

 nition. The shells are all orbicularly lens-shaped in form, and, beyond an 

 occasional tinge of yellow or fulvous rust, they are characteristically de- 

 void of colour. The animal, so far as it has been observed by M. Valen- 

 ciennes and Professor Forbes, differs materially from either Donax or Tel- 

 Una. It has no protruding siphons, the siphonal orifices being sessile, and 

 the foot is peculiar in being much elongated and tubular. The branchiae 

 are also distinguished by the pair of leaflets being united on each side into 



VOL. II. R 



