148 PALAEONTOLOGY OF CALIFORNIA. 



lated or striate internally; Trilonidea has a tooth on the posterior 

 part of the columellar lip, and the other genera are obviously un- 

 tenable. 



P. CRASSUS, n. s. 

 PI. 26, Fig. 26. 



Shell small, pyriform, heavy; spire low, whorls five, rounded; 

 suture impressed. Surface marked by prominent revolving ribs, 

 crossed by irregular longitudinal ribs or lines ; these latter are 

 variable in size, number, and disposition, generally having a more 

 or less regular arrangement, being of about the same size as the 

 revolving ribs, and producing nodes or tubercles on the latter 

 where they cross ; between the larger markings are very numer- 

 ous fine lines of growth. Aperture broad in the middle, acute 

 behind; outer lip simple, inner lip incrusted; canal moderate and 

 slightly twisted. 



Length, .62 inch ; width, .45 inch; length of aperture, .5 inch. 



From the Shasta Group, from a canon in the foot-hills, a mile south of the road 

 from Colusa to the Sulphur Springs, near the eastern margin of the Coast Eange, 

 Colusa County. Eare. 



ERIPACHYA, N. Gen. 



Shell short, robust, subovate to subfusiform, spire moderately 

 elevated. Aperture broad, terminating in advance in a very short 

 canal or a mere notch; outer lip simple; inner lip more or less 

 heavily incrusted. Surface marked by longitudinal ribs and re- 

 volving lines. 



The present genus is proposed to receive three species described in Pal. Cal., 

 Vol. 1, under the name of Neptunea, but which possess a series of characters in 

 common, sufficiently different from the typical species of that genus, to warrant 

 their separation. They are small shells, about an inch in length, robust, thick, and 

 want entirely the recurved canal of Neptunea; and they cannot, with any greater 

 propriety, be placed in any of the other described genera of the family. They are 



