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University of California Publications. 



[Geology 



Tritonium impressum, n. sp. 



Pl. 13, Fig. 3. 



The shell is moderately long. The spire is elevated. The 

 number of whorls is five. The second whorl is .about one-third 

 the height of the body whorl. The surface of the whorls is mod- 

 erately convex. The mouth is broad. The suture is deep. The 

 surface is marked by numerous small longitudinal ribs. The 

 varices are moderately large but few. 



Dimensions: — The distance from base to apex is 28 mm., and 

 the maximum width of the body whorl 14 mm. 



Occurrence : — Three miles southwest of Martinez and west of 

 the Del Hambre Canon road. It occurs in the upper beds only. 



Tritonium eocenicum, n. sp. 



Pl. 13, Fig. 4. 



The spire is moderately elevated. The whorls are five in 

 number, possibly six. They support broad, prominent transverse 

 ribs, of which there are about twelve on the body whorl. These 

 ribs are slightly oblique and may be almost sinuous. They are 

 about one-half as broad as the interspaces. These ribs are crossed 

 by numerous well marked revolving striae. The few varices are 

 well marked. Only one specimen was found. 



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

 10 mm. The maximum width is 6.5 mm. 



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

 tinez, on the east side of the road to "Walnut Creek. It has been 

 found in the upper beds only. 



Tritonium pulchrum, n. sp. 



Pl. 13, Fig. 6. 



This shell is fusiform and turreted. The spire is high and the 

 number of whorls is eight. They are sharply angulated and the 

 slope nearly straight above. The body whorl is convex below. 

 The surface is marked by numerous longitudinal and revolving 

 ribs. Upon the body whorl are twenty-six revolving ribs. Nine 

 of these were above and seventeen below the angle. The varices 

 are very prominent, about ten in number on each whorl, and 

 support prominent nodes on the angles of the whorls. 



