Vol. 4] Weaver. — Palaeontology of ihe Martinez Group. 121 



Dimensions: — Distance, measured from apex to base, is 34 

 mm. The maximum width of the body whorl is 16 mm. 



Occurrence : — About two and one-half miles south of Mar- 

 tinez and on the west side of the road to "Walnut Creek. Its geo- 

 logical range is confined to the upper Martinez beds. 



Fusus aequilateralis, n. sp. 



Pl. 13, Fig. 7. 



The shell is small and elongated. The whorls number six. 

 They are very convex and prominently angulated. The upper 

 and lower faces are equal and slightly convex. The suture is 

 distinct. The spire is high. The canal is long and straight. The 

 surface of each whorl is marked by nine or ten quite large nodes 

 on the angles. This form resembles Fusus martinezensis very 

 closely, but differs in the greater length of the spire, in the 

 prominence of the angles upon the whorls, and in the nodes upon 

 the angles. 



Dimensions: — The distance, measured from apex to base, is 

 21 mm. The maximum width of the body whorl is 8 mm. 



Occurrence : — The type specimen was obtained about five 

 miles south of Martinez and one and one-half miles north of 

 Grayson Creek. It occurs only in the lower beds. 



Perissolax tricarnatus, n. sp. 



Pl. 13, Fig. 9. 



Shell elongated, spire moderately elevated. Whorls six in 

 number. The body whorl is ornamented by three prominent 

 revolving earinae. The upper two form prominent nodose angles 

 on the whorl and separate a slightly concave middle portion from 

 the sharply sloping upper and lower areas. A short distance 

 below the lower of these two angles is the third carina, which is 

 less prominent and is scarcely nodose. The remaining whorls 

 show only the upper carina. The aperture is elongated and 

 narrow. The presence of the three revolving ridges on the body 

 whorl seems to be a constant character for all specimens collected 

 in this region, and, as no intermediate forms appear, it seems 

 best to regard this as a new species, distinct from Perissolax 

 blakci Gabb of the Tejon. 



