A. E. Verrill — Mollusca of the New Emjlattd Coast. 435 



is thin, but bears, just in front of the beak, a large, strong, crescent- 

 shaped tooth, convex within, projecting upward nearly at right angles 

 to the margin, and hollowed out on its upper side, at the lunular 

 depression, so that the entire thickness of the tooth is situated within 

 the outline of the edge ; another very much smaller, triangular tooth 

 is situated under and behind the beak, within and below the margin. 

 The exterior ligament is small and thin. 



Length, 8"^"' ; height, the same. 



Station 2,229, oft" Chesapeake Bay, in 1,423 fathoms. One dead 

 specimen (No. 44,838.) 



Tapes, sp. 



At station 2,206, in 1,043 fathoms, a single, somewhat eroded left 

 valve of a Tapes was dredged, which agrees very closely in size, 

 form and general appearance with T. virgineus of Europe. It is, 

 perhaps, a little more oblong, or less convex ventrally, and the con- 

 centric ridges are finer, closer, and less raised, or more like lines of 

 growth. The hinge-margin is thicker and stronger. The pallial 

 sinus is smaller, narrower and more pointed. 



Length, SB""™; breadth, 22'"'" (No. 40,108.) 



Choristodon (?) cancellatus Verrili/sp. dov. 



Shell rather small, swollen, triangular-ovate, with the umbos prom- 

 inent and swollen, and the beaks large, subspiral, and turned forward, 

 so that in a front view the shell has a strongly^ cordate form. The 

 anterior end is shoi't and broadly rounded ; the posterior end is 

 longer and narrower, somewhat tapered, obtusely rounded at the 

 end. The posterior dorsal margin slopes rapidly, and is subparallel 

 with the ventral margin. There is a small, depressed, distinct, but 

 not much differentiated lunular area in front j of the beaks. The 

 scuhjture consists of numerous narrow, nearly equal, sharply cut, 

 radiating grooves, separated by wider raised ridges, which are 

 decussated by thin, sharp, raised, concentric lines ; these two sets of 

 lines, in crossing each other, jjroduce a rather fine cancellated struc- 

 ture over the entire surface. The hinge consists of two strong cen- 

 tral teeth just below the beak, separated by a triangular pit, and 

 supported on a rather broad plate, extending inward from within 

 the thickened margin ; the posterior of the two teeth is largest and 

 thickest, and may have been slightly bilobed when perfect. A thin, 

 incised ligameutal groove runs from under the beak backward in a 

 curved line between the thickened inner and outer shell-margins. 

 Muscular and pallial scars are not visible, owing to erosion. 



