The West American Scientist. 



Vol. IL San Diego, Calif., April, 1886. No. 15. 



MOLLUSKS OF SAN DIEGO.— II. 



[Continued from page 4-] 



Cerostoma nuttalli, Conrad, is distinguished from the preceding shell by the 

 absence of the wing-like varices. It is abundant on the r«cky beaches, some of the 

 pure white or banded varieties being quite pretty. 



Muricidea barbarensis, of Gabb, is quite rare. One large and old specimen has 

 been found at Pt. Loma, inhabited by a hermit crab, which was seven-eighths of 

 an inch long. Muricidea incisa, Brod., is easily distinguished by the dark brown or 

 black bands which are very prominent in the beach worm specimens that are occas- 

 ionally washed ashore. This species is some times found living near low-water mark. 



Pteronotus festivus, Hinds, found abundant among small, angular boulders in 

 sheltered places, is distinguishable from Murex trialatus by the characteristic re- 

 curving of the wing-like expansions of the shell. In some old specimens these are 

 worn off when it is more difficult to identify and might be mistaken for Cerostoma 

 nuttallii but for its slenderer appearance. 



The Ocinebras are mainly small, stout shells. A single specimen only of Ocine- 

 bra subangulata, of Stearns, is known from San Diego, a beautifully colored indi- 

 vidual of this species having been found on kelp in 1883, which is now in the 

 museum of the Philadelphia Academy of Science. Nuttall's Ocinebra poulsonii is 

 somewhat larger and of duller color.s being dingy white marked by revolving black 

 lines. The shell grows to a length of nearly two inches, and is found abundantly 

 with pteronotus. 



Ocinebra circumtexta, Stearns, of which only a few young specimens have been 

 collected at San Diego, approaches the purpuras in general appearance. The shells 

 referred to in Proceedings U. S. Nat. Mus., VIII, 535, under the name 'interli- 

 rata,' belong to this. 



Ocinebra interfossa, and gracillima, are small shells and abundant under stones 

 partially imbedded in shell sand. 0. interfossa is distinguished by a coarse net-like 

 sculpturing, and is smaller and less abundant than gracillima. 



One of the most common shells on this coast is Purpura saxicola, the ' rock 

 purple,' which derives its generic name from the fact that the ancient Tyrians ob. 

 tained a purple dye from the bodies of a similar species. It is less than an inch 

 long, and possesses a short spire, flattened columella, thin outer lips, short canal and 



