Clark: The San Lorenzo Series of Middle California 183 



Clavella gravida Gabb?, Dall, U. S. Geol. Surv., Bull. 590, p. 23, 1914. 

 Agasoma gravidum Gabb, English, Univ. Calif. Publ., Bull. Dept. Geol., 



vol. 8, no. 10, pp. 244, 251, pi. 25, figs. 7, 8, 1914. 

 Agasoma gravidum Gabb, Clark, Univ. Calif. Publ., Bull. Dept. Geol., 



vol. 9, no. 2, pp. 15, 18-20, 1915. 



Agasoma gravidum is very closely related to A. columbianum 

 Anderson and Martin. 155 The sculpturing of the two forms is nearly 

 identical ; both vary considerably in the prominence of the nodes, the 

 heaviness of the collar and the distance between the first row of nodes 

 and the collar. On the majority of the specimens of A. columbianum, 

 which the writer has seen, the collar is heavier, there is a deeper 

 excavation just below the collar, and the first row of nodes is situated 

 farther away from the collar than on A. gravidum. On A. colum- 

 bianum there is a tendency for the third row of nodes below the 

 collar to be nearly obsolete ; on the majority of specimens of A. gravi- 

 dum, this row is well developed; the species varies, however, in this 

 respect for on some specimens the third row is nearly obsolete ; this 

 appears to be so on the type as figured by Gabb, who mentions the 

 fact of its variability. The two forms are so similar and their vari- 

 ability so great that the writer prefers to consider A. columbianum 

 as a subspecies of A. gravidum. 



AGASOMA GBAVIDUM MULTINODOSUM, n. var. 

 Plate 23, figure 5 

 Type specimen 11266, Coll. Invert. Palae. Univ. Calif., loe. 2754 

 This form was found at a number of localities associated with the 

 typical Agasoma gravidum, from which it differs in the following 

 respects : The body whorl is somewhat broader in proportion to the 

 height of the shell ; the nodes are more numerous ; the three rows of 

 nodes on the body whorl are connected by faint longitudinal ribs ; 

 the anterior row of these nodes is almost obsolete ; the spiral ribbing 

 anterior to this row is heavier than on the typical A. gravidum. 



Genus CLAVELLA Swains 



CLAVELLA CALIFOBNICA, n. sp. 



Plate 23, figure 8 



Type specimen 11238, Coll. Invert. Palae. Univ. Calif., loe. 76 



Shell medium in size ; spire high, acute ; number of whorls seven or eight. 

 Sutures slightly depresed, with a well-defined, narrow tabulation which is about 



is-' Proc. Calif. Acad. Sei., ser. 4, vol. 4, p. 73, pi. 5, figs. 6a, 66, 1914. 



