74 CONCHOLOGY. 
M. hamatus.* M. lateralis.* 
M. croceus.* M. Californianus.* 
M. cubitus.* M. leucopheeatus.* 
2. Genus Modiola. Pl. VIII. 
Animal. As above. - 
Separated by Lamarck from the Mytilus, on account of its 
being more transverse than longitudinal, the beaks instead of being 
terminal are placed beneath the apex. 
Shell. Smooth, subtransverse, equivalve, regular, subtriangu- 
lar, posterior side short; summits nearly lateral; hinge toothless, 
linear and lateral ; ligament partly interior, situated in a marginal 
furrow ; one sublateral, elongated muscular impression in each 
valve. Inhabits the British and American seas. Thirty-two 
species. 
Modiola Guyanensis. Modiola Papuana. 
M. pulex. M. tulipa. 
M. discors. M. albicosta. 
M. cinnamorea. M. vagina. 
M. plicata. M. picta. 
M. lithophaga. M. sulcata. 
M. Adriatica. M. plicatula. 
M. discrepans. M. semifusca. 
M. trapezina. M. purpurata. 
M. silicula. M. barbata. 
M. semen. M. caudigera. 
M. levigata. M. squamosa. 
M. securis. 
M. Americana.* M. capax.* 
M. castanea* ’ M. recta.* 
M. opifex.* M. Carolinensis.* 
M. semi-costata.* 
3. Genus Pinna. PI. VIII. 
Animal. Body oval, elongated, moderately thick, enveloped in 
