ACADEMY OF NATURAL SCIENCES. 173 



Lima, Brug. 



L. Erringtoni G. Shell very oblique, sides subparallel ; beaks small; ante- 

 rior end prominently rounded, sloping with a broad curve below to the base : 

 posterior side nearly straight, continuing upwards in a long narrow ear; ante- 

 rior ear obsolete (?). 



Surface marked by strong concentric undulations, crossed on the upper and 

 posterior portions by fine radiating lines. 



Length, 2.25 inches ; width, 1. inch. 



The specimens are all very much compressed, and may be somewhat distort- 

 ed in form, though the outlines are very nearly uniform in all of the spe- 

 cimens. 



PnOLADOMYA, SOW. 



P. orbiculata G. Compressed, sub-circular ; beaks rather prominent, nearly 

 central; anterior end and base regularly rounded; posterior end slightly pro- 

 duced, more prominent below than above. Surface ornamented by concentric 

 ribs, irregular in size, crossed by undulating, radiating lines on the anterior 

 half of the shell. These lines become gradually obsolete and disappear on or 

 about the middle of all of the specimens, although more perfect examples 

 might show them continuing further. 



Height, from a slightly distorted specimen, 1.1 inch ;_ width, 1.3 inch. 



Like the preceding species, all of the specimens have suffered considerably 

 by compression ; and had we perfect specimens, the shell would be found to be 

 quite convex. 



Belemnites. 



B. Pacificus G. Long, slender, tapering very gradually and with a slight 

 convexity to the tip. Section, sub-elliptical ; alveolus deep and narrow. 



A specimen 3 inches long, measures .35 in. in diameter in the middle. One 

 cast has been found with a diameter of .9 inch at the broadest part. 



I first discovered this species, as imperfect casts, in the slates near Spanish 

 Flat, El Dorado County. Since then, numerous fragments and casts have 

 been found at Mariposa, by Mr. C. R. King and Miss Errington. 



Communication on the San JLuis Obispo Quicksilver 



Fossils. 



BY WM. M. GABB. 



Mr. Attwood has recently presented to the collection of the State Geological 

 Survey, a series of Fossils collected by himself, in the formation in which the 

 San Luis Obispo cinnabar deposits occur. 



Through the kindness of Prof. B. Silliman, Jr. I have had the opportunity 

 of examining another small collection, made by that gentleman, at the same 

 locality. I consider the result of sufficient interest to warrant a special com- 

 munieation on the subject. 



