1917] Nomland: The Etchegoin Pliocene of Middle California 239 



species: Area trilineata Conrad, Chrysodomus portolaensis (Arnold), 

 Dendraster gibbsii (Remond), Olivella biplicata Sowerby, Paphia 

 staminea (Carpenter), Peeten, ef. healcyi Arnold, Peeten terminus 

 Arnold. 



PECTEN ETCHEGOINI Anderson 

 Plate 7, figures 1 to 5 

 Peeten etchegoini Anderson, Proc. Calif. Acad. Sci., vol. 2, p. 198, pi. 18, 

 figs. 92-93, 1905. 



Peeten wattsi, var. morani Arnold, IT. S. Geol. Surv. Prof. Paper 47, pp. 



121-122, pi. 10, figs. 3-6, 1906. 

 Peeten wattsi Arnold, var. etchegoini Anderson, U. S. Geol. Surv. Bull. 



396, p. 77, 1909. 



On obtaining a large number of specimens from the type localities 

 of Pecten etchegoini Anderson, P. nutteri Arnold, and P. wattsi 

 Arnold a difficulty was at once experienced in attempting a separation 

 of these forms. By closer study it was found that the prominence of 

 the ribs of P. etchegoini varies greatly. Also the nodose constrictions 

 characteristic of P. wattsi vary much in prominence. It became evi- 

 dent that series could be found for both valves showing a gradation of 

 P. nutteri and P. wattsi into P. etchegoini. Figures are given in the 

 present paper showing gradational series. P. nutteri Arnold and 

 P. wattsi Arnold are therefore here used as variations of P. etchegoini 

 Anderson. 



SEBPULA (?), sp. 



Figure 2 , 



On the south bank of Garza Creek, in the Coalinga district, is 

 exposed a bed composed almost exclusively of tubules believed to 

 represent the genus Serpula. The tubules are about 1.5 mm. in 

 diameter and are closely packed together, forming an almost solid 

 mass. 



Pig. 2. Serpida {?), sp. X 2. 



