80 PALAEONTOLOGY OF CALIFORNIA. 



BACULITES, Lam. 

 B. CHICOENSIS. 



PL 17, Fig. 27, and 27 a; PL 14, Fig. 27, 6, and 29, and 29 a. 

 (Bac. Chicoensis, Trask. Proc. Cal. A. N. S., 1856, p. 85, PL 2, Fig. 2.) 



SHELL elongated, very slightly tapering, section varying from 

 subelliptical or ovoid to subtriangular ; dorsal side narrowest, 

 sometimes marked by a narrow, square carina. Sides smooth, or 

 ornamented by broad, slightly prominent, curved ribs, which have 

 their convexity downwards and the longest limb on the dorsal 

 side. Mouth (restored from lines of growth) deeply emarginate 

 on the sides, with a long lip on the dorsal side, and a shorter one, 

 not more than half as high, on the ventral side. Septum on the 

 same plan as in B. anceps. Dorsal lobe broad, with a small 

 tongue-like projection in the middle and a minute spur on each 

 side; terminal branches forming nearly half the length of the 

 lobe, bifid at the end, with a short side branch at the base, one 

 small spur above. Dorsal saddle deeply divided into two double 

 branches. Superior lateral lobe a fourth longer than the dorsal, 

 terminating in two narrow parallel branches, each ending in three 

 spurs with a tooth above on each side ; above these branches the 

 lobe suddenly widens, and bears on each side an oblique, robust 

 branch, with a shorter one above it, and sometimes a small spur 

 above this. Lateral saddle larger than the dorsal, and a little 

 more minutely divided. Inferior lateral lobe a little shorter and 

 slightly broader than the superior lateral, divided for a third of 

 its length into two double branches, each one ending in two 

 unequal spurs ; between these, the excavation is either simple or 

 bears a single minute tooth ; above these, on the dorsal side, are 

 three small spurs, and on the ventral side two larger ones. Ven 

 tral saddle minute and simply notched. Ventral lobe not more 

 than a third as long as the preceding, ending in three spurs, with 

 two or three above. 



