PROCEEDINGS OF THE NATIONAL MUSEUM. 187 
Genus HETERODONAX Morch. 
Heterodonax bimaculatus D’Orb. 
Plentiful at San Pedro. 
PEO 
Heterodonax bimaculatus, var. purpureus. 
This purple variety is common with the type. 
Heterodonax bimaculatus, var. salmoneus. 
a This variety is salmon-pink, and is rare. Some shells have also been 
found that are canary colored. 
: Family MACTRIDA. 
Genus MACTRA Linné. 
Mactra (Standella) californica Conr. 
Two single valves. These valves are each nearly 5 inches long. 
‘ Mactra (Standella) planulata, var. falcata Gld. 
Often washed ashore in the spring. (W. H. D.) 
Mactra (Standella) nasuta Gld. 
Not plentiful. This shell is of a blue-white color, with a dingy gray, 
epidermis, and is thinner than the former species. Of the Mactrid, 
| Mr. Dall says, “names at present must be provisional.” 
Genus LABIOSA Schmidt. 
Labiosa undulata Gld. (Raeta undulata Gray). 
Single valves washed ashore in winter. Pairs not separated are very 
rare. 
Family VENERID®. 
Genus CALLISTA Poli. 
Callista (Amiantis) callosa Conr. (Dione nobilis Reeve). 
This graceful bivalve is found at low tide in winter, in the bay; ocea- 
sionally washed ashore. 
Callista (Lioconcha) Newcombiana Gabb. Pl. xxii, Fig. 4. 
Two shells and three or four valves; Catalina. 
Genus TIVELA Link. 
sTivela crassatelloides Conr. (Pachydesma crassatelloides Conr.). 
One of our “economic mollusea,” but not as plentiful as the Chione. 
The largest shells are often used by local artists as plaques, on which 
Ihiniature pictures of ‘old missions,” ete., are painted, These shells 
