1885.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 539 



calcareous than the shell in general, without callus or any thickening, 

 twisted into an open spiral, continuous with the outer lip in front only ; 

 aperture very oblique, subquadrate, Alt. 15 ; max. lat., 17 ; long, of 

 aperture, 12 ; lat. of aperture, lO"*'". 



This shell was first received from Mr. Henry Hemphill at San Diego; 

 subsequently other specimens came to hand from Cape St. Lucas. 

 As will be seen from the characters of the soft parts, it is a true Lamel- 

 laria {Marsenia, Leach, is a later and synonymous name). It is more 

 inflated and elevated than any European or West American form known 

 to me. 



Lamellaria stearnsii Dall (1871) is a depressed and much more calcare- 

 ous species, which has the soft parts translucent white, and the shell dis- 

 tinctly finely striated. Lamellaria rhomhica Dall proves to be a Mar- 

 senina, though the shell does not greatly differ from that of L. stearnsii, 

 and should take the name of Marsenina rhomhica. The two forms of 

 L. stearnsii, one of which was described as a variety orbiculata, may 

 turn out to be only sexually distinct, as the differences are such as 

 mark the two sexes of the common British species according to Jeffreys. 

 Both the just mentioned forms, as well as Marsenina rhomhica^ were 

 collected at Monterey ; while L. diegoensis seems to belong to the south- 

 ern fauna. D.] 

 Crucibulum spinosum Sby. 



Common rocks and shells along bay shores. 

 Crepidxila adunca Sby. 



Not rare on Norrisia Norrisii. 

 Crepidula mgosa Nutt. 



Abundant on Pecten cequisulcatus and other shells and stones in San 

 Diego Bay, Todos Santos Bay and elsewhere. 

 Crepidula navicelloides Nutt. 



Abundant in the interior of dead univalves, varying in size according 

 to the shell occupied. 



In dead bivalves assuming the form nummaria Gould. 

 Crepidula dorsata var lingulata Gld. 



Abundant on rocks at La Playa and elsewhere. Very variable in form, 

 but well marked by the form of the deck. 



Hipponyx tumens Cpr. 



Abundant with the next species. 

 Hipponyx antiquatus L., var. serratus Cpr, 



Abundant under stones or shelving rocks, ocean beaches. 

 Scalaria hindsii Cpr. and var. subcoronata. 



Not common. 

 Scalaria indianorum Cpr. 



Not rare ; San Diego. 

 Scalaria bellastriata Cpr. 



Very rare. San Diego. 



