166 CALIFORNIA ACADEMY OF SCIENCES. 



Rare in the lower San Pedro series at San Pedro; common in the upper San 

 Pedro series at Los Cerritos, but rarer in the same horizon at Deadman Island and 

 San Pedro. Found also in the Pleistocene at Twenty-sixth Street, Sail Diego. 



Living. — Santa Barbara to San Diego (Cooper). 



Pleistocene. — San Pedro (Cooper; Arnold): San Diego (Arnold). 



112. Semele pulchra Soum-by. 



Plate XV, Figs. 1 and la. 



Aviphidesma pulchra Sv,Y., Conch., Vol. Ill, No. 2, fig. 2. 



Semele pulchra Sby., Carpenter, Brit. Assn. Rept., 1863, p. 640. Gabb, Pal. Cal., Vol. II, p. 94, 

 1869. Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 264. Keep, West Coast Shells, 

 p. 190, 1892. Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 1S6. Dall, 

 Trans. Wagner Inst. Sci., Vol. Ill, Part 5, 1900, p. 995. 



Shell small, oval, thin ; beaks turned forward ; posterior sides shorter than the anterior, 

 slightly biangular; fold not very distinct; anterior dorsal margin slightly convex ; anterior end evenly 

 rounded ; surface sculptured with numerous fine, sharp concentric ridges, and fine radiating 

 striations; interior as in .5*. decisa except more delicate, and cardinal tooth in each valve prominent. 



Dimensions . — Long. 22 mm.; alt. 18.2 mm.; diam. 6 mm. 



Distinguishable from S. decis,a by smaller, thinner shell, finer concentric 

 sculpture and radiating striations. Specimens of the species in the State Museum 

 Collection at the University of California, Berkeley, are labeled S. Jiavescens Gld. 

 Specimens identified by Dr. Dall. 



Rather rare in the upper San Pedro series at San Pedro and Los Cerritos. 

 Found also in the Pleistocene at Twenty-sixth Street, San Diego. The specimen 

 figured is from the upper San Pedro series at San Pedro, and is now in the collection 

 of Delos Arnold. 



Living. — Santa Barbara to San Diego; Acapulco to South America (Cooper). 

 Pleistocene. — San Pedro (Cooper; Arnold): San Diego (Cooper; Arnold). 



113. Semele pulchra ^overby, montereyi, var. nov. 



Platk XV, Figs. 4 and 4a,. 



Shell small, oval, ventricose, thin; beaks quite posterior to middle of shell; anterior dorsal 

 margin long, nearly straight; anterior extremity evenly curved; posterior end much shorter than 

 anterior, evenly rounded; fold obsolete; cartilage-process deep, oblique; one prominent cardinal 

 tooth in each valve; lateral teeth distinct; pallia) sinus very large, rounded, expanded interiorly. 



Dimensions. — Long. 23 mm.; alt. 17.5 mm.; diam. 11.5 mm. 



Resembles *S'. -pulchra in size, but is much more oval, lacking the angular 

 appearance at the beak; the beaks are situated more anteriorly in var. montereiji and 

 the shell is much more ventricose. Easily difTcrentiated from the typical S. palchra. 

 Pronounced a new variety of pulchra by Dr. Dall. 



Rare in lower San Pedro series at Deadman Island. 



