29 



or enveloped by other substances, but affixed to ma- 

 rine bodies, generally in numerous groups, by a tough 

 membranous peduncle, sometimes a foot long; the shell 

 is very flat, composed of five valves, two placed on each 

 side faintly striated, the fifth or dorsal one smooth, with 

 sulcated sides, longer and narrower than the others, 

 all of them united together and kept in their proper 

 position by a thin membrane. 



Anatifera lsevis Anatifera dentata 



villosa striata 



Anatifera vitrea. 



POLLICIPES 



LEPAS POLLICIPES. — Linnmis. 



Mawes Linn. f. 8, pi. 2. 



Dr. Leach established this genus, which is easily dis- 

 tinguished from others somewhat resembling and al- 

 lied to it. The shell consists of thirteen or more valves, 

 the smallest at the sides, which are very flat and com- 

 pressed, the peduncle short, wrinkled, rigid, and often 

 covered with small scales like shagrine. 



Pollicipes cornucopia Pollicipes mitella 



Pollicipes scalpellum. 



