114 



University of California Publications. 



[Geology 



DESCRIPTION OF SPECIES. 

 Pelecypoda. 

 Lima multiradiata Gabb. 



Lima multiradiata Gabb, 1869, Palaeontology of California, Vol. II, p. 

 201, PI. 33, fig-. 101. 



This shell is large, moderately convex and only slightly 

 oblique. The posterior side forms an irregular curve from the 

 ear to the base. The anterior margin is concave from the ear to 

 a point midway to the base, and is regularly convex below thai 

 point. The surface is covered with numerous radiating ribs, 

 each of which in the vicinity of the margin is narrower than the 

 interspaces. These ribs have a somewhat wavy appearance. The 

 surface is also marked by several large and numerous smaller 

 well defined lines of growth. 



Dimensions : — The measurements of two specimens are given. 

 The maximum height of a cast of the first is 92 mm. Its greatest 

 width is 88 mm. The second specimen, also a cast, has a maxi- 

 mum length of 106 mm. and a width of 96 mm. The margins 

 of both these specimens are more or less broken away. When 

 restored the maximum width of the casts would about equal the 

 distance from beak to base. These shells closely resemble Lima 

 multiradiata Gabb as described by Stanton from Lower Lake. 

 They differ in that they are less oblique and much wider. The 

 width is one-third greater in proportion to the distance from 

 beak to base than in the case of Lima multiradiata as described 

 by Stanton. Although somewhat different in form, it seems best 

 to consider these specimens as multiradiata. 



Occurrence : — This form occurs about three miles to the 

 southwest of Martinez, in the hills to the west of Del Hambre 

 Canon. As yet it has been found only in the lower half of the 

 Martinez Group. 



Modiola merriami, n. sp. 



Pl. 12, Fig. 2. 



The shell is thin, elongated and moderately convex. The 

 beaks are broad and not very prominent. The umbonal ridge is 

 prominent, rounded, and curved only slightly downward. The 

 surface is marked by several rather prominent concentric 

 wrinkles. There is no radial ornamentation. 



