280 University of California Publications in Geology [Vol. 7 



long, about 0.35 wide. The backward curve of the growth lines above 

 the carina suggests a Pleurotomoid shell, which is partly confirmed by 

 the curve forward of the posterior margin of outer lip remaining, but 

 the general form is so similar to that of Gabb 's Potamides diadema, 

 that I have placed it in that genus until better known. (See Pal. of 

 Cal., 1, p. 130, pi. 20). Eesembles Pleurotoma (Perrona) spirata Lamk. 

 Marysville Buttes, one specimen from Cret. B, Mr. Watts. ' ' 



Dimensions: Length of smaller specimen figured 10mm; 

 width of body-whorl 4mm. 



Cooper's type specimen is much larger than the small one 

 figured, but it does not show the canal or inner lip. The canal 

 is long and straight and the inner lip is smooth. The body-whorl 

 is marked by three prominent carinae in addition to the finer 

 revolving lines. 



In the type, an older specimen, the space between the first 

 and second carinae on the body-whorl is sharply notched inward, 

 the vertex of the notch being central. The smaller specimens 

 vary much in the strength of the vertical ribbing. The small 

 specimen figured was found at University of California Locality 

 1853. 



CORDIERA GBACILLIMA Cooper 

 Plate 12, figure 3 



Cordiera gracillima. — Cooper, J. G., Catalogue of California Fossils, 

 Bull. 4, California State Mining Bureau, p. 41. 1894. 



"Very slender, fusiform; first two whorls smooth, turbinate; third 

 with about twelve oblique subvertical riblets, which decrease to seven 

 on sixth whorl, narrow, meeting at sutures, and with four revolving 

 riblets crossing them, one along suture. A wide interval between this 

 and the next anterior, forms an obtuse angle on whorls, continuing to 

 the upper third of body-whorl, below which the vertical ribs disappear. 

 On body-whorl about eight revolving riblets cross these, with three or 

 four fine ones between each, and twelve to fifteen others below angle 

 pass around the canal. (The shells being imbedded in rock the exact 

 number of vertical ribs cannot be distinctly seen, whether seven or 

 eight, and the outer lip is too much broken to see the form of the sinus, 

 but it must be very shallow.) Mouth very narrow, sharp above, widest 

 at angle of lip, below curving to the left, gradually forming the canal. 

 Columella with four plaits at middle, the upper one, strongest. Length, 

 0.48 inch; breadth, 0.09; mouth, 0.14 long, 0.03 wide; canal, 0.10 long. 



The figure is twice the natural size of the one specimen found at 

 Marysville Buttes by Mr. Watts. This is a decidedly different shell 

 from the two species figured and described by Mr. Gabb, both of which 

 were also found in Santa Ana Mountains, Orange County, by Dr. Bowers, 

 but in a very poor condition." 



