REPORT ON THE BRACHYURA. 285 



The genus differs from ScaJopidia chiefly in the form of the 

 merus of the maxillipeds, which is quadrate in that genus, in 

 the character of the epistome which in Scalopidia is not sharply 

 separated from the buccal cavity, in the movable eyes which 

 are not concealed beneath the carapace, in the swollen basal 

 joint of the antennula and the cylindrical ambulatory legs. 



Chasmocarcinus typicus sp. now PI. vn, Figs. 3-5. 



Orbits transverse; sternum and abdomen granulate. 



Length of carapace a little more than three-fourths of the 

 posterior width. Front and orbits about one-half the width 

 of the carapace. The upper surface is convex and rounds 

 gradually downward into the lateral surfaces which are almost 

 perpendicular. Anterior third strongly deflexed. Lateral 

 margin as seen from above, convex and slightly emarginate 

 at its middle; at this point a deep sulcus arises and extends 

 obliquely downward and forward, joining the inferior hori- 

 zontal suture. The anterior half of the lateral margin is de- 

 fined by a slight ridge of fine granules; the posterior half is 

 not defined. The cardiac region is well marked, also the 

 posterior part of the mesogastric. Surface finely granulate. 

 Front with a short and shallow median sulcus; margin trans- 

 verse, faintly bilobed. Orbit about two-thirds the width of 

 the front; upper margin transverse. Eye fitting closely in 

 the orbit, and much thicker at the base than at the cornea. 

 Below the orbit there is an oblique ridge subparallel to the 

 inferior margin. The margin of the epistome is notched in 

 the middle, on either side of the middle, and again above the 

 summit of the endognath of the maxillipeds. The maxillipeds 

 are separated by a hiatus equal in breadth to the maxilliped. 

 The ischium of the endognath has subparallel sides. The 

 outer margin of the merus is semicircular, the inner margin 

 slightlv convex; at its base about half the width of the ischium. 

 The sternum is finely granulate, the abdomen sparsely so. In 

 the male the widest part of the abdomen is at the suture be- 

 tween the third and fourth segments; outline of fourth to 

 seventh segments inclusive, triangular. In the female, the 



