486 A. E. Verrill—3IoUusc<i. of the New England Coast. 



Length, 8""" ; lieight, '/">'"; thickness, 6'""' ; beak to posterior end, 

 7'"'" ; to anterior end, 2""". 



Station 2,265, oif Chesapeake Bay, in 70 fathoms. One dead and 

 somewhat eroded left valve (No. 44,839). 



The precise generic position of this shell is doubtful, owing to the 

 imperfect preservation of the specimen, which does not show the 

 muscular and pallial scars. 



Cryptodon grandis VerrlU and Smith, sp. nov. 

 Plate XLIV, figure 22. 



Shell rather large, thick, angular, remarkably high, owing to the 

 great j)rominence of the ventral margin and the elevation of the 

 beaks, and with the surface strongly undulated by median and pos- 

 terior folds. The beaks are high, acute and strongly incurved and 

 turned forward. The lunule is large, cordate, sunken, and defined 

 by a prominent ridge. The posterior dorsal margin has a long, nar- 

 row, fusiform ligamental area, bordered by a prominent, rounded 

 ridge. Another larger and more prominent ridge extends from the 

 beaks to the angle, leaving a sunken concave area behind it, and ter- 

 minating in a prominence or lobe at the margin. Another broad and 

 distinctly elevated, rounded ridge runs from the beak to the ventral 

 margin, which projects downward in a prominent, rounded angle ; 

 this median ridge is divided into two parts by a slight furrow just 

 behind the middle. Anteriorly there is a ridge, not very well marked, 

 running from the beaks outside the lunular area and terminating in a 

 rounded projection of the anterior margin. Thus the margin has an 

 anterior and two posterior prominences, besides the great median 

 lobe, while the anterior margin, in the lunular region, is strongly con- 

 cave and the posterior dorsal margin is convex. The surface is dull 

 grayish white, and closely covered with prominent and often sharply 

 raised lines of growth, which are irregular and wavy or fibrous in 

 appearance. The hinge-margin is thin, with a narrow, elongated liga- 

 mental groove, which is strengthened by a narrow buttress within; 

 there are rudiments of teeth. 



Length of the largest specimen, 21""" ; height, from beak to ven- 

 tral margin, 24""" ; breadth 15""". 



A large living specimen was taken at station 2,231, in 965 fathoms, 

 N. lat. 38° 29', W. long. 73° 00'. Five valves, some of them nearly 

 as large, were taken at station 2,228, in 1,582 fathoms. A small dead 

 specimen (No. 35,757) was taken in 1883, at station 2,111, off Cape 

 Hatteras, in 938 fathoms. 



