DESCRIPTIONS OF GENERA AND SPECIES. 199 



the hind margin of the body : the two front pairs are 

 almost blade-like; so that when seen on edge they 

 appear almost linear, but they are rarely seen in this 

 position ; they are usually turned at an angle, so that 

 the side is partly seen. Thus they look very broad : 

 they are much curved. The only remarkable feature 

 is the tarsus (fig. 5), which is a generic feature, and 

 is described in treating of the genus (p. 195). There 

 is a short curved spine on the under side of the tarsus, 

 a strong spike on the under side of the tibia, and some 

 fine hairs, as seen in the plate. The two posterior 

 pairs of legs are quite different from the anterior ; 

 they are ordinary rounded legs, rather small, but with- 

 out any special feature. The tarsi are of the ordinary 

 nature, and are terminated by large, single, curved 

 claws (fig. 6). 



The Ventral Surface (figs. 2 and 3). The sternum 

 is a triangular chitinous plate sending out band-like 

 projections on each side parallel to the edge of the 

 rostral collar ; and a similar, but straight, posterior 

 band in the median line ; which is longer in the male 

 than in the female. The epimera of the first pair of 

 legs are formed by the lateral projections of the 

 sternum and a branch arising from the sternum and 

 passing behind the legs. Those of the second pair of 

 legs are somewhat Y-shaped sclerites, which in the 

 male are joined at their posterior ends to the posterior 

 end of the sternum by short cross-pieces. In the 

 female they are wider apart, and not attached. The 

 epimera of the third and fourth pairs of legs are short, 

 right-angled pieces in the male ; they are not apparent 

 in the female. The vulva is situated between the 

 two posterior pairs of legs, but advances further 

 forward than the insertions of the legs ; it is protected 

 anteriorly by a large, semi-annular, chitinous band 

 (the sternite of Robin), and has well-marked chitinous 

 labia. The male organ (fig. 9) lies rather further 

 back; it is protected by a slightly elliptical (almost 

 circular) plate, slightly truncated posteriorly. This 



