NO. 1788. NORTH AMERICAN EROASILID^— WILSON. 371 



BOMOLOCHUS CONCINNUS, new species. 

 Plates 54 and 55. 



Female. — General body form like that of Cyclops; cephalothorax 

 one-half wider than long, with a rounded posterior margin and pro- 

 jecting sides. Free segments diminishing regularly in size; genital 

 segment considerably enlarged, half as wide again as the fifth seg- 

 ment, and barrel shaped, with the sides strongly convex. Abdomen 

 three-jointed, the basal joint considerably the largest; anal laminae 

 oblong, three-quarters the length of the last abdomen joint and 

 tapered posteriorly, each armed with four setse, two short ones on 

 the sides of the lamina and two long ones at its tip, the inner one 

 longer than the outer. Egg cases about half the entire length, ante- 

 riorly the same width as the genital segment, but narrowed posteri- 

 orly; eggs in five or six longitudinal rows, about seventy or eighty 

 in each case. 



First antennae slender and similar to those in exilipes, except that 

 the basal joints are almost entirely covered by the carapace in dorsal 

 view. Two long tactile hairs are inserted close together and near the 

 center of the anterior margin of the fused basal portion, and there is 

 an extra long plumose seta at the distal end of this portion on the 

 dorsal surface. The three slender terminal joints carry these antennae 

 far beyond the lateral margins of the carapace. In the second 

 antennge the anterior surface of the second joint and a portion of the 

 ventral surface of the basal joint are covered with transverse ridges. 

 The anterior surface of the two terminal joints is covered with longi- 

 tudinal rows of short spines; the terminal claws on the last joint are 

 interspersed with spines and setse, making a dense tuft. 



The labrum is transversely elliptical, twice as wide as long, with a 

 smooth surface. The mandibles have a smooth and slender cutting 

 blade about the same length as the basal joint. The first maxillas 

 project moderatel}'' from the ventral surface, and are each armed 

 with four widely divergent plumose set^. The second maxillae are 

 simple, the terminal blade conical and covered with fine hairs. The 

 maxillipeds are large, with a terminal claw long enough to reach the 

 proximal end of the second joint. The tip is acute and there is a 

 short curved accessory claw on the outer margin near the center. 

 To the base of this claw on its outer side is attached a large plumose 

 seta; another much smaller one is attached to the tip of the second 

 joint inside the terminal claw; a third, and by far the largest of the 

 three, is attached to the ventral surface of the second joint close to 

 its inner margin and points backward. 



The first legs have a two-jointed exopod, the basal joint unarmed, 

 the terminal one with six large setae. The endopod is three-jointed; 

 each of the two basal joints carries a single huge seta on its inner 



