40 AMERICAN JOURNAL 



Dimensions. — Lengtli "SS incli ; width '50 inch ; diameter 

 •30 inch. 

 Habitat, Lower California, in Haliotis. — AY. ISTewdomb, M. D. 



My Cabinet, Cabinet of Dr. AYesley Newcomb. 



Observations. — Except in size this shell much resembles 

 P. penita, Conr.; besides being much smaller than that spe- 

 cies, it may be distinguished from it by its smaller anterior 

 area, and its greater solidity. 



3. P. CUEVATA, Tryon.— pi. 2, f. 6, 7, 8. 



Description. — Shell narrow, mnch lengthened, accuminate 

 posteriorly. Surface marked as usual in the genus, the area 

 anterior to the furrow, comprising rather more than a third of 

 the total width. Posterior to the furrow, the shell is curved 

 downwards or upwards, and frequently to one side. Posterior 

 margin reflexed. Posterior dorsal plate very small, somewhat 

 pentagonal, pointed anteriorly. 



Dimensions. — Length '30 inch : width '70 inch ; diameter 

 •28 inch. 

 Habitat, Straights of Fuca. — W. M. Gabb. 



My Cabinet. Cabinet of Mr. Gabb. Cabinet of the Academy 

 of Natural Sciences. 



Observations. — This species, which comes from a quite 

 northern locality, is readily distinguishable by its narrow 

 elongate form, and by its curiously curved posterior portion 

 and minute accessory valve. 



These two new species of Penitella are particularly interest- 

 ing additions to the Molluscous fauna of the West Coast, inas- 

 much as they prove the genus to be larger than was supposed, 

 and variable in size and other characters ; and also that it in- 

 habits a considerable extent of the coast. 



