CRETACEOUS FOSSILS. 189 



valve a slight thickening under the beak, and in the left valve an 

 obsolete tubercle ; pallial line unknown ; internal margin entire. 



I propose this genus on the shell described in the first volume of Pal. Cal., as 

 Loripes dubia. The figures there given of the hinge are not good, the engraver 

 not having faithfully followed my drawings. The tubercle in the left valve 

 especially, is represented as too well-defined. The genus seems to be a member of 

 the Lucinidce, though from our ignorance of the shape of the mantle margin, the 

 ultimate reference must yet remain an open question. 



C. dubius, Gabb. 



(? Loripes dubia, Gabb ; Pal. Cal., Vol. 1, p. 127, pi. 74, fig. 170, 171.) 

 Peculiar to the Chico Group. 



LUCINA, Brug. 



The references to the plates of L. nasuta and L. postice-radiata, in Vol. 1, were 

 transposed, bj~ mistake, in the text. They should read, L. nasuta, PI. 24, Pig, 159, 

 and L. postice-radiaia, PI. 24, Pig. 158. By reading the descriptions, the error 

 becomes at once obvious. 



CRASSATELLA, Lam. 



C. grandis, Gabb. 



(C. grandis, Gabb ; Pal. Cal., Vol. 1, p. 181, pi. 24, fig. 163.) 

 (C. alta, Con. ; Pacific R. R. Report, Vol. 5, p. 321.) 

 (C. alta, Con.; Smithsonian Check List, Eocene, No. 104.) 

 (Not C. alta, Con. ; Tert. Poss., p. 21, pi. 7.) 



In my description of this species, I pointed out sufficiently the specific differ- 

 ences between the two forms. Another character, however, has since been dis- 

 covered in the lunule, with which I was then unacquainted. In C. alta it is deeply 

 impressed, the sides being vertical, the base flat, and the sides forming right angles 

 both with the adjoining portion of thesurface and with the floor of the depression. 

 In C. grandis the lunule is equally deep and longer, but its margin is rounded, and 

 the sides convergent, there being no flat space at the base. 



