260 



BULLETIN 166, UNITED STATES NATIONAL MUSEUM 



ventrally and evenly arcuate from before backward. Posterior 

 margin concave and about three-fifths as long as anterior margin. 

 Surface smooth. First three abdominal segments visible from above, 

 remaining four bent under the body, forming a broad oval plate equal 

 in size to the carapace. Ocular peduncles large, subconical, not in 

 distinct orbits ; corneae devoid of pigment. Antennules large, exserted ; 



FiGCEE i6.—Hapalocarcinu^ marsupialis, female: a, Dorsal view, xl3; 6, antennae and antennules; c, third 

 maxilliped; d, chela. After Caiman. 



antennae 5-jointed. Buccal area very large. The third maxilHpeds 

 do not nearly cover the buccal cavity and are widely separated from 

 each other at the base by a semicircular area of the sternum. Ischium 

 flattened, subtriangular, widening from a narrow base, its antero- 

 internal angle produced forward, rounded and fringed with setae; 

 merus articulated with the outer end of distal margin. Exopod 

 rudimentary, epipod well developed. Chelipeds rather stout, about 



