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University of California Publications in Geology [Vol. 8 



ribs of the left valve are broadly rounded to flat-topped. The radiating 

 ribs of the flat right valve of P. andersoni Arnold are distinctly 

 rounded, but not as narrow-topped as those of the left valve. The 

 radiating ribs of the right valve of P. raymondi are broad and usually 

 flat-topped. P. andersoni Arnold appears to be characteristic of the 

 Monterey or Temblor Horizon. The writer has never seen it in the 

 Upper Miocene. 



P. raymondi, n. sp., is a common and a very characteristic species 

 of the Upper Miocene. It is very common in the San Pablo of Middle 

 California and also in the Scutella breweriana zone. It is also very 

 common in the "Santa Margarita" in the southern part of the state. 



Named in honor of Professor W. J. Raymond of the University 

 of California. 



Dimensions. — Large specimen figured, height, 50 mm.; length, 

 50 mm. ; diameter, 7 mm. 



Occurrence. — University of California localities 1942, 1947, 1946, 

 1478, 136, etc. ; also from the Scutella breweriana zone in Middle 

 California and from the Santa Margarita of the southern part of the 

 state. 



PECTEN (CHLAMYS) PABLOENSIS Conrad 

 Plate 47, figure 8; plate 48, figure 2 

 1857 Pecten pabloensis Conrad, Pae. E. B. Eept., vol. 6, pt. 2, 1857, pp. 

 71, pi. 3, fig. 14. 



1888 Pecten pabloensis Conrad.? Cooper, 7 th Ann. Eept. Calif. State 



Mineral., 1S88, p. 25S. 

 1898 Pecten (? Plagioctinium) pabloensis Dall. Trans. Wagner Free Inst. 



Sei., vol. 3, pt. 4, 1898, p. 703. 

 1906 Pecten pabloensis Conrad. Arnold, Prof. Paper U. S. G. S. no. 47, 



p. 88, pi. XXVII, figs. 6, 6a (not fig. 5 and 5a or 7). 

 1909 Pecten pabloensis Conrad. Weaver, Univ. Calif. Publ. Bull., Dept. 



Geol., vol. 5, no. 6, p. 262. 

 1912 Pecten pabloensis Conrad. Smith, Proc. Calif. Acad. Sci., 4th series, 



vol. III. 



Shell thin, medium in size, nearly equilateral, inequivalved ; height 

 about equal to width; apical angle averaging about 90°; hinge line 

 about half the length of the shell ; dorsal edges gently concave ; pos- 

 terior dorsal edge longer than anterior dorsal edge ; anterior ears 

 slightly longer than posterior ears. Right valve sculptured by seven- 

 teen to nineteen low, rounding ribs with interspaces averaging a little 

 wider than the top ribs ; a fine narrow riblet in each interspace. Sur- 

 face also sculptured by fine, imbricated, concentric lines which, when 



