l68 NEW YORK STATE MUSEUM 



but differs from it in the same respect as well as in the less angular 

 termination of the umbonal ridge and in having the ventral and 

 dorsal margins more nearly parallel. 



Edmondia magdalena nov. 



Shell small, oblique, very elongate for the genus, nearly twice as 



long as high. Umbones inflated, protruding above the hinge which 



is nearly straight and extending about six-tenths the 



length of the shell. Posterior margin subtruncate, 



rounding below into the elliptical ventral border 



Edmondia mag- which coutinucs in an elliptical curve to the hinge. 



dalena nov. x2 ^ ^ " 



Cast of left valve. Bcak 2 mm from the anterior end of the hinge. The 



Cape le Trou ^ 



Grindstone I. dcfails of Ornamentation are not well shown on the 

 cast, but there are fine, even concentric striae and the usual undu- 

 lations of the genus. 



Dimensions. Length, 9^mm ; height, 5+mm ; hinge, 6+mm. 



Remarks. This species is similar to E. h a r 1 1 i Dawson, but is 

 much smaller and the hinge slopes less steeply anteriorly, and it is 

 slightly more truncated on the posterior end. 



Parallelidon hardingi Dawson? 



1\I a c r o d o n hardingi Dawson. Acadian Geology, p. 302, fig. 102, 



1878. 



One small specimen probably belongs to this species. It is on a 

 slab with Sanguinolites insecta Daw. 



Parallelidon dawsoni nov. 



Shell small, subquadrangular, beaks very convex and 



arched over the cardinal area. Anterior end short, don har- 

 dingi Daw- 

 abruptly rounding: downward and backward into the sfently son. ^ wind- 



sinuate ventral margin. Posterior lateral edge evenly and 



abruptly rounded into the truncated posterior margin which reaches 



the hinge at a slightly obtuse angle, the anterior and posterior 



borders being nearly parallel. The length of the 



hinge is equal to the length of the shell and its 



direction nearly parallel to the ventral margin. 



Parallelidon daw- The cast shows fine couceutric lines and larger 



Tr. "orTndSre L growth variccs. 



Dimensions. Length, 13.5 mm; height, 7 mm; beak, 4.5 mm 



from front. 



Remarks. In illustrating his species, P. h a r d i n g i, Dawson 



used two specimens, one (fig. 102a) a very short, highly gibbous 



specimen, quite convex beneath the beaks and on the ventral margin 



