BIVALVES MYTILUS. 



G{ 



PsiUacea. 



Tridentata. 



Spondyloidcs. 



*Truncata. 



Reticularis. 



riicatella. 



•Ciispa. 



•Lacuiiosa. 



Pubescens. 



*Cusi)idata. 



Farcta. 



Caput-serpcntis. 



♦Terebratula. 



Aiigulata. 



Hysterita. 



Biloba. 



Veiitricosa. 



Grvphoides. 



iraiidalium 



Flexuosa. 



Rugosa. 



VlacvntA {Chinese window O.) 



Sella {Saddle O.) 



♦Spiiiosa. 



Aculeata. 



Muricata. 



Squama. 



Punctata. 



Ujidulata. 



Capensis. 



Detriincata, 



Sanguinolenta. 



Mtrea. 



Cranium. 



Cylindrica. 



Nucleus. 



Avenacea. 



MYTILUS.— Mlscle. 



Animal allied to an Ascidia: shell bivalve^ rongh^ gene- 

 rally affixed by a byssus or beard of silky filaments: 

 hinge mostly withoxU teethy with generally a subulate 

 excavated longitudinal line. 



Of the gemis Mytilus there may be enumerated sixty- 

 four species j though some of these are a little iudistiuct, 



