1912] 



Clark: Neocene Section at Kirker Pass 



57 



preserved. The following species have been collected from the 

 upper beds : 



Modiolus multiradiatus Gabb. 



Faunal Zones. — Because of the meagerness of the fauna in 

 the Upper Division it may possibly seem premature to assume 

 the presence of two faunal zones in the San Pablo series 

 corresponding to the two divisions as described. It would seem 

 reasonable to suppose that the absence of certain species from 

 the upper beds that are found in the lower could be ac- 

 counted for by the larger representation of individuals in the 

 latter, but the absence of certain species in the lower beds 

 that are found in the upper would not indicate that this is the 

 correct explanation of the difference. Some indication of zonal 

 difference between the faunas of the upper and lower divisions 

 is found in the presence in the Upper Division of the follow- 

 ing species not known in the Lower Division : Astrodapsis whit- 

 ne\ji, Pseudocardium gabbi, Littorina, sp. b., Littorina, sp. c, 

 Corbicula calif ornica, and Trophon ponderosum. In the Upper 

 Division two new species of Littorina are found which are not 

 found in the Lower Division, while Littorina remondi and Lit- 

 torina, sp. a are not found in the Upper Division. In the 

 Lower Division a new species of Corbicida is found which is 

 not found in the Upper, while Corbicula calif ornica, so common 

 in the upper beds, has not been found in the Lower Division. 



Practically the entire fauna of the San Pablo at Kirker Pass 

 belongs to shallow water. Quite a number of species, such 

 as Corbicula, Ostrea, and Littorina, are either fresh-water or 

 brackish-water forms. 



n. varf 



Cardium quadrigenarium Conrad. 

 Corbicula ealiforniea Gabb. 

 Uryptomya ealiforniea ? Conrad. 

 Cryptomya oralis Conrad. 

 Littorina, n.sp., b. 

 Littorina, n.sp., c. 

 Macoma, n.sp. Conrad. 

 Maeoma seeta Conrad. 



Astrodapsis whitneyi Eemond. 

 Calliostoma splendens Carpenter, 



Mya japonica Gray. 

 Pecten, n.sp. 

 Peeten discus Conrad. 

 Pecten pabloensis Conrad. 

 Platoydon cancellatus Conrad. 

 Pseudocardium gabbi Remond. 

 Saxidomus nuttalli Conrad. 

 Solen sicarius Gould, n. var. 

 Calyptraea filosa Gabb. 

 Trophon ponderosum Gabb. 

 Zirphaea dentata Gabb. 



