REPORT OF THE DIRECTOR IQIO I7I 



mm ; the height at extremity of hinge, about 7 mm ; greatest length 

 of the shell, 12 mm. 



Remarks. The ends of our specimen are missing. The shell is 

 very similar in form to Hind's figure of P. 1 a t u s McCoy, and 

 the dimensions are similar, relatively, though our specimen is much 

 smaller. It also seems to be related to shells from the Waverly of 

 Ohio. 



Cardinia subquadrata Dawson? 



Cardinia subquadrata Dawson. Acadian Geology, p. 304, fig. 108, 

 1878. 



A poor cast, the generic and specific determinations doubtful. 



Schizodus richardsoni nov. 

 Cast of valve small, form oblique, characteristic of genus. Beak 

 subtriangular, narrowly inflated ; umbonal ridge elevated and gently 

 angular; anterior end of shell short, rapidly curving downward into 

 the elliptical ventral margin which terminates in 

 the angular upward turn at the end of the um- '^^ 



bonal ridge. Posterior truncated margin nearly ,,. 



straie^ht and almost vertical, reaching: the hinge „ , . , 



=> . . Schizodus rich- 



at an ans^le of about 120^ leaving^ a relatively ^^^^fp^i "ov. 



° ^ fe ^ Cast of left valve. 



larg'e concave triangular area above the um- Cape le Trou, Orind- 



° . ° , stone I. 



bonal ridge and below the hinge. 



Dimensions. Height, 9 mm ; length, 1 1 mm ; length umbonal 

 ridge, 10 mm. 



Remarks. This species is much like S. ellipticus Hall, 

 from the Hamilton. It seems to dififer from it in the front of the 

 shell being shorter and the posterior margin reaching the hinge at 

 a larger angle. The beak is thus made a little more prominent. It 

 differs from S. i o w e n s i s in having a relatively longer, straighter 

 hinge while the area between the hinge and the umbonal ridge js 

 proportionately larger and the posterior truncation more nearly 

 vertical. Our specimens are closely related to both species. 



Aviculopecten lyelli Dawson 



Aviculopecten lyelli Dawson. Acadian Geology, p. 305, 

 fig. iiia-c, 1878. 



Cast of left valve subovate, beak pointed, protruding 1.5 mm 

 beyond the hinge. Shell moderately convex ; anterior ear triangular, 

 separated from the shell by a sulcus, rounded at the extremity; 

 margin separated from that of the shell by a deep sharp sinus. 

 Posterior ear somewhat larger, triangular, less sharply separated 



