CONCHOLOGY. 47 



American seas, in cavities, which they bore in rocks or wood. 

 Nine species. 



Saxicava rugosa. Saxicava pholadis. 



S. gallicana. S. Australis. 



S. veneriformis. 



S. distorta.* S. carditoides.* 



S. rhomboides.* S. californica.* 



2. Genus Petricola. PI. VII. 



Jnimal. Unknown. 



Shell. Subtrigonal, more or less irregular, transverse, inequi- 

 lateral ; upper side narroved and a little gaping ; lower side 

 rounded ; hinge with two teeth in each valve, or in one valve 

 only. Inhabits the Australian seas, boring into wood and rocks. 

 Thirteen species. 



Petricola lamellosa. Petricola recellaria. 



P. Ochrolenca. P. exilis. 



P. Semilamellata. P. ruperella. 



P. lucinalis.- P. chamoides. 



P. striata. P. pholadiformis. 



P. costellata. P. labagella. 



P. linguatula. 



3. Genus Venerirupis. PI. VII. 

 Animal. Unknown, but probably resembling the Venus. 

 Another lithophagous shell, taken from the genus Venus, and 



distinguished from it by the different disposition of the teeth. 



Shell. Transverse, inequilateral, posterior side short, the an- 

 terior gaping slightly. Hinge with two teeth on the right valve, 

 three on the left, and sometimes three on both — these are small, 

 near together, and parallel. Ligament exterior. Inhabits the Bri- 

 tish seas, boring into rocks and clay. Eight species. 



Venerirupis perforans. Venerirupis exotica. 



V. nuclea. V. distans. 



V. Ira. V. crenata. 



V. corditoides. V. alata. 



