CRETACEOUS FOSSILS. 153 



revolving angles, between which, and above to the suture, are 

 very minute revolving striae ; in advance of the lower angle, these 

 strise are larger and alternate in size; besides these the whole 

 surface is covered with longitudinal raised lines corresponding to 

 the striae of growth. 



Length, .37 inch < width of body whorl, .18 inch ; length of aperture, .2 inch. 

 A single specimen from the Tejon Group, Martinez ; Mathewson. 



CORDIERA, Rouault. 



C. MITR.EFORMIS, n. S. 

 PI. 26, Pig. 32. 



Shell elongate, mitrseform, spire comparatively low ; number 

 of whorls unknown ; body whorl concave, angulated and undu- 

 lated above, long, slender, and sinuous below. Aperture long 

 and narrow, biangular posteriorly, narrowing gradually in ad- 

 vance ; outer lip thin, obliquely emarginate between the angle 

 and the suture, very slightly sinuous, nearly straight below ; inner 

 lip rather heavily incrusted, and bearing two (possibly three) 

 oblique folds near the middle; canal produced, straight; suture 

 impressed, linear, slightly irregular. Surface bearing ten or 

 eleven prominent, slightly oblique longitudinal ribs, starting from 

 the angle of the whorl, and becoming obsolete before reaching 

 the middle ; crossing these are numerous revolving ribs, small 

 above the angle and large and rounded below. 



Length (less the greater part of the spire), .9 inch ; length of aperture, .65 inch ; 

 width of body whorl, A inch. 



This beautiful little shell has no near relatives in form, either in the genus, or 

 among its associates in the formation, in other genera. Its discovery is of especial 

 interest, since it is only the second known Cretaceous species of the genus, the 

 other being also Californian ; and this being by far the oldest species yet discovered. 

 The existence of its congener in the Tejon Group was one of the numerous argu- 

 ments used by an eminent authority, in support of his view of the Tertiary age of 

 that formation ; while we now have the genus carried back to near, if not to the 



PAL. VOL. II. — 21 



