112 CALIFORNIA ACADEMY OF SCIENCES. 



This is the type form and is distinguishable by acutely pointed ears, distinct, 

 squarish ribs and wide shell. Specimens identified by Dr. Dall. 



Common in upper San Pedro series of San Pedro, Los Cerritos, Crawfish 

 George's, Deadman Island, San Pedro, and Long Beach; rare in lower San Pedro 

 series of Deadman Island and San Pedro. Found also at Spanish Bight and 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 (Carpenter). 



Pleistocene. — Santa Barbara; San Pedro (Cooper): San Pedro (Arnold): San 

 Pedro; San Diego (Dall): San Diego (Arnold). 



32. Pecten (Chlamys) latiauritus Con., var. fragilis, var. nov. 



Plate XII, Fig. 8. 



Shell of same general type as P. latiaziritus. More compressed and much thinner; ribs 

 seven to nine, very low and rounded, with shallow, rounded interspaces; surface smooth, the 

 concentric sculpture being nearly obsolete ; hinge long, ears sharply pointed. 



Dimensions. — Long. 26 mm.; alt. 26 mm.; diam. 78 mm.; hinge 25 mm. 



Distinguishable from var. jliicicolus Dall, which it resembles, by having a 

 longer hinge-line and pointed ears. 



Rare in upper San Pedro series of San Pedro and Los Cerritos. The speci- 

 men figured is the type, which is from the upper San Pedro series at San Pedro, and 

 is now in the United States National Museum. 



Pleistocene. — San Pedro (Arnold). 



33. Pecten (Chlamys) latiauritus Con., var. monotimeris Con. 



Plate XII, Figs. 4 and 4a. 



Pecten monotimeris Con., Jour. Phil. Acad. Sci., Vol. VII, 1837, p. 233, PI. XVIII, fig. 10. Carpenter, 

 Brit. Assn. Rept., 1863, p. 645. Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 257. 

 Keep, West Coast Shells, p. 167, fig. 140, 1892. 



Pecten latiauritus \zx . monolimerisQ.o-s.,T)K\A., Trans.Wagner Inst. Sci. , Vol. Ill, Part 4, 1898, p. 709. 



Shell resembling P. latiauritus, but more oblique, inflated, and markedly shorter, with 

 smaller ears. 



Dimeiisions. — Long. 19 mm.; alt. 20 mm.; diam. g mm. 



Rare in lower San Pedro series of Deadman Island and San Pedro, and in 

 upper San Pedro series of Los Cerritos, San Pedro, Long Beach, and Crawfish 

 George's. Found also in Pleistocene of Spanish Bight, San Diego, and Barlow's 

 ranch, Ventura. 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 (Dall). 



Pkiniocene. — Santa Barbara; San Pedro (Dull): San Pedro; San Diego; 

 Ventura (Arnold). 



