Maryland Geological Survey 369 



ing from C. conradi. The dactylus is irregularly ovate in transverse sec- 

 tion, having an acute, finely crenulated cutting edge, even with the outer 

 side, the grasping face within this cutting edge being slightly concave and 

 receding, then rounded, there being no angle along the inner edge of the 

 grasping face. The back of the dactylus has two contiguous angles, one 

 irregularly crenulated, the other finely and regularly crenulated. Later- 

 ally, on the outside, the dactylus has a rounded longitudinal rib, and a 

 series of punctures lies in the concavity between this rib and the cutting 

 edge. 



Length of palm 10.2 mm. ; breadth 7.5 mm. 



The carpus (of another individual) is very short and broad, sharp- 

 edged, produced into sharp lateral angles distally; concavity for the con- 

 dyle of the merus small. Length 8 mm. ; width 12.4 mm. 



In the type specimen the carpus is largely concealed in a very hard 

 nodule, which could not be further removed without danger to the speci- 

 men. The manus has lost a large part of the surface on the exposed side, 

 and the tips of the fingers. Another hand which has lost the fingers has 

 two longitudinal series of punctures, four in each, on the outer side. It is 

 also somewhat broader. Length of palm 13.5 mm.; width 10.8 mm.; 

 thickness 4.7 mm. In this species the convexity of the two sides of the 

 hand is less unequal than in C. mortoni, and the lateral edges are nearly 

 straight, not deflected near the proximal angle, as in that species. The 

 shape of the carpus is very different, if I am right in associating the 

 example of this with the manus found at the same place. 



Named for Dr. Wm. Bullock Clark, director of the Survey. 



Occurrence. — Matawan Formation. Post 105, Chesapeake and Dela- 

 ware Canal. Delaware. 



Collection. — Maryland Geological Survey. 



Callianassa sp. undet. 



Plate X, Fig. 7 



Description. — Two hands from the Chesapeake and Delaware Canal, the 



palmar aspect of one of them drawn in fig. 6, are probably either the 



smaller claw of Callianassa or from one of the small perseopods. The 



