CRETACEOUS FOSSILS. 205 



shallow sinus at the middle of its base, bearing three or four of these folds ; a cor- 

 responding tongue or prolongation of the other valve meeting it, but without the 

 usual median depression on the surface. Among between twenty-five and thirty- 

 specimens, not one shows all the surface of a valve, though by counting several, 

 it seems that there are nearly sixty of the small ribs and about fifteen of the large 

 marginal folds. 



IIADIATA. 

 SMILOTROCHUS, E. & H. 



? S. CURTUS, 11. S. 

 PI. 34, Fig. 106, 106 a. 



Polypidom circular, low, base apparently rounded or very 

 blunt, sides but slightly diverging. Internal septa short, numer- 

 ous, leaving a well-marked cup-like cavity in the middle; their 

 sides marked by numerous small, curved, raised lines, radiating 

 from below upwards and inwards. External surface unknown. 



Figures, natural size. 



Rare near Martinez. Two specimens in my collection from either the Martinez 

 or Chico Groups ; found by Mr. Mathewson. This coral is easily distinguished 

 by its short, robust, cup-like form. The surface sculpture is lost on both the speci- 

 mens, being torn away by the hard matrix in which they were embedded. 



