34 NEW YORK STATE MUSEUM 



beaks arc situated about one third the hinge length from the anterior end 

 and the region in front of the beaks is somewhat excavated. The hight of 

 the shell is about one third of the length. The surface is covered by 

 concentric lines only. 



Horizon. Nos. 9, 10, 11. 



Cypricardella norumbegae Clarke 



Plate t), figures 14 



Cypricardella norumbegae Clarke. N. V. State Mus. Bui. 107. 1907. p. 227 



Shell short, subrectangular, broader behind than in front, beaks well 

 forward, umbones prominent, umbonal ridge well developed and dividing 

 the valves so as to leave a broad postumbonal slope which is slightly 

 depressed or concave. Hinge line short, not extended in front. Shell mar- 

 gin curving from a broad anterior extremity with an outward bend into the 

 basal margin which becomes direct near the umbonal ridge where it turns 

 sharply almost at right angles, curving outward, upward and forward and 

 joining the hinge in an obtuse angle. Hinge with the characteristic median 

 tooth just beneath and in front of the beak on the left valve. 



Shell substance thick, surface with regular concentric growth lines and 

 sometimes a vague radial fold in the postumbonal slope. 



Horizon. Nos. 9, 11, 13. 



Macrodus matthewi Clarke 



Plate 4, figures 15-18 



Macrodus matthewi Clarke. N. Y. State Mus. Bui. 107. 1907. p. 234 



Shell quite small, obliquely ovate, much broader behind with obliquely 

 curving lower margin and broadly rounded posterior extremity. The hinge 

 is not long and slopes at its posterior end to the posterior curve. The 

 beak is well forward, nearly terminal, umbones prominent, umbonal ridge 

 arched, oblique, high, fading out posteriorly. A broad sinus lies medially 

 in front of the umbonal ridge and produces an inward curve on the lower 

 shell margin. Length and posterior hight of the shell nearly the same. 



Species name. Dr G. F. Matthew, Canadian geologist. 



Horizon. Nos. 10, 11. 



Macrodus ? baileyi Clarke 



Plate 4, figures ig, 20 



Mac rutins ? baileyi Clarke. X. Y. State Mus. Bui. 107. 1907. p. 234 



Shell small, elongate, gradually expanding backward. Beaks at about 

 one third the length of the hinge from the anterior extremity. Hinge line 

 rounding broadly backward. Umbonal ridge or crcscence line high, posterior 



