ROBERTSONIA. Wa 
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. Ropurtsonta TENUIS (Brady and Robertson). 
Pl. XLI, figs. 1—14. 
Hetinosoma tenue, B. & R. Proceedings of the British Associa- 
tion, p. 196 (1875). 
Length 4th 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 
antennee 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 asin the female. Posterior antenne 
(fig. 4) 2-jointed, the large basal joint giving attach- 
ment to a slender, biarticulated inner branch, which 
