204 



University of California Publications in Geology [Vol. 9 



Arnold, Pecten estrellanus Conrad var. terminus Arnold, and Echina- 

 rachnius gibbsii Remond have been found to have a range extending 

 throughout the fossiliferous portion of the beds. A large number of 

 species thought not to extend below the Etchegoin have been found 

 to be of frequent occurrence in the Jacalitos. Among others may be 

 mentioned Turns (Bathytoma) coalingensis (Arnold), Trophon coal- 

 ingensis Arnold. Calliostoma coalingensis Arnold. Pecten wattsi 

 Arnold, which has been considered characteristic of the beds of 

 Etchegoin age, has been found at one locality well down in the Jacalitos. 



Palaeontologic Determination op Age op the Jacalitos Beds 



By increasing the Jacalitos fauna from 37 specifically determined 

 forms to 82, the number listed in this paper, the close relationship of 

 the Etchegoin and Jacalitos at once becomes apparent. Fifty-nine 

 of the species listed in this paper are known to be present in the 

 Etchegoin or younger formations. Twenty-six species are found also 

 in the Santa Margarita-San Pablo and these are chiefly forms of long 

 range. 



The probable Pliocene age of the Jacalitos and Etchegoin has 

 already been shown by the work of Professor J. C. Merriam 6 and the 

 writer 7 for beds of corresponding age north of Coalinga. 



Description op Species 



ASTRALIUM AENOLDI, n. sp. 

 Plate 10, figures 2a, 2b 

 Shell heavy, moderately elevated, five or more whorls, slightly 

 convex at shoulder and periphery. Ornamented by about seven spiral 

 cords, of which the anterior two are the heaviest. Incremental lines 

 well defined, unequal ; the crossing of these by spiral sculpture gives the 

 shell a nodose appearance. A wide sulcus occurs between the lower 

 of the heavy anterior cords and suture. Aperture oval, with thin outer 

 lip. Base flatfish, with about twelve nodose cords and wider inter- 

 spaces. Umbilical region imperforate, concave, with peripheral and 

 low median ridges. Dimensions of type : height, 48 mm. ; maximum 

 diameter, 48 mm. ; minimum diameter, 38 mm. 



e Merriam, J. C, Tertiary Vertebrate Faunas of the North Coalinga Region, 

 Trans. Am. Philos. Soc, vol." 22, part 3, Philadelphia, 1915. 

 Univ. Calif. Publ. Dept. Geo!., vol. 9, no. 6, 1916. 



