Class VI. MYTILUS. MUSSEL. 235 



GENUS XVII. MYTILUS. MUSSEL. 



Animal, allied to an Ascidia. 



Shell often affixed to some substance by a 

 beard. 



Hinge without a tooth, marked by a longitu- 

 dinal hollow line, sometimes crenulated. 



Gm. Lin. 3350. 



Mont. Test. Br. 166. 



1. CRISTA 



Lin. Tr. viii. 104. 





GALLI. 



* M. with a plaited spinous shell, marked near 

 the margin with a series of protruding points. 

 Found adhering to bottoms of ships. 



Lin. Syst. 1156. No. Q4g. Lin. TV viii. 105. 2. rugosus. 



Gm. Lin. 3352. Mont. Test. Br. 164. 



List. Angl. tah. iv. fig. 21. 



M. with a brittle shell, very rugged, and in 

 shape most irregular; usually oblong, and 

 rounded at the ends. Length nearly an inch. 

 Color whitish. 



Always found lodged in limestone. The out- 

 side generally appears honey-combed ; but the 

 apertures are too small for the shell to pass 



