BOBERTSONIA. 25 



basal joint and two small branches ; anterior foot-jaw 

 short and broad, posterior 3-jointed, well developed, 

 forming a prehensile hand. First four pairs of feet 

 nearly alike, each branch 3-jointed ; fifth foot foliaceous, 

 2-jointed. Last joint of the inner branch of the second 

 pair in the male converted into two or three strong 

 spine-like processes. 



1. ROBERTSONIA TENUis (Brady and Robertson). 

 PI. XLI, figs. 114. 



Ectinosoma tenue, B. & R. Proceedings of the British Associa- 

 tion, p. 196 (1875). 



Length - 2 ^th of an inch. Moderately robust ; head 

 united with the first thoracic segment, and pro- 

 duced into a long falcate rostrum (fig. 1) ; abdomen 

 distinctly narrower than the cephalothorax, and com- 

 posed of five segments, the posterior margins of which 

 are finely spinulose, and have three or four somewhat 

 larger spines at the outer angles (fig. 14). Anterior 

 antenna3 8-jointed, short, only about half the length of 

 the first body- segment ; in the female densely beset on 

 the outer margin with long hairs, some of which are 

 strongly pectinate (fig. 2) ; in the male (fig. 3) the 

 joints are irregularly swollen at the distal, and con- 

 stricted at the proximal extremities ; the fifth joint is 

 produced on the outer margin, and bears a thick, club- 

 like appendage (fig. 3a), the limb altogether being not 

 so densely setose as in the female. Posterior antennas 

 (fig. 4) 2-jointed, the large basal joint giving attach- 

 ment to a slender, biarticulated inner branch, which 



