188 SHELLS OF SAN PEDRO BAY—WILLIAMSON. 
are from 5 to 54 inches in length, but [ have one that measures 6 inches, 
and weighs 22 ounces. The large shells soon lose their epidermis, so 
smaller ones are preferred for cabinet specimens. 
Genus PSEPHIS Cpr. 
Psephis tantilla Gld. 
Rare. Arnold. 
Genus VENUS Linné. 
Venus toreuma Gld. (Venus Fordii Yates). 
Valves not rare at Catalina Island. Two perfect examples found on 
the island. Two or three valves reported from San Pedro Bay. Dr. 
Yates’s figure agrees perfectly with Gould’s type. (W. H. D.) 
Genus CHIONE Megerle. 
Chione fluctifraga Sby. 
This and the two following species belong to our ‘economic mol- 
lusca,” although this is the least abundant of the three. 
Chione simillima Sby. 
Our most plentiful Chione. This species shows some variation. 
Chione succincta Val. 
In mud flats, with the two former species. 
Chione undatella Sby. (=C. excavata Cpr. of California). 
Worn valves comparatively plentiful at Catalina Harbor, in 1890. 
“The extreme limit north for it.” (W. H. D.) 
Genus TAPES Megerle. 
Tapes grata Say. 
‘I‘wo shells found by two collectors. (W.H. D.) 
Tapes laciniata Cpr. 
Seldom found alive, 
Tapes staminea Conr. 
This “economic mollusk” of our coast is smaller than the other forms 
of this genus. 
Tapes staminea, var. diversa Sby. 
A few with the type. 
Tapes tenerrima Cpr. 
Rare; dead. 
