140 



JAMES WATERSTON. 



narrow, band-like, broadest subapically and nearly bare, there being a few bristles 

 dorsally on both sides towards the apex. Of these 5-6, longer, run in a slanting row 

 from beyond half on the dorsal edge to the lower apical angle on the anterior aspect. 

 Tibia with an apical comb of 5-6 peg-like spines, spnr just shorter than first tarsal 

 joint. Tarsal joints (in ratio 26:17:12:12:23) with the following heavy spines 

 respectively on the anterior edge :■ — 6, 2, 2, 1, 0. Hind legs with the coxa very broad 

 (8 : 9) and flat, with two long bristles above the trochanter and 4-5 in front ; femur 

 (19 : 5) shorter than tibia, with a row of 6-8 ventral and subventral bristles. Tibia 

 (11:2): the upper apical angle bevelled off and the comb (10-11 spines) continued 

 round it on the posterior edge. Anteriorly there are two spurs, both short, and the 

 upper one about half the lower or one-third of the width of the tibia. Tarsal 

 proportions nearly as in mid-leg, the first and second joints shorter (24 : 16). 



Fig. 2. Fore whig of Diver sinenus silvestrii, $. 



Abdomen shorter than thorax and about twice the head in length ; spiracle minute, 

 circular. The tergites (2-6) bear at the sides (2-3, 2-3) widely separated bristles. 

 Along the sides of the abdomen is a row of single bristles, two at most on each overlap 

 (fused pleurite). Free portion of sheath ^ of the base. 



Length, ri-l*2 mm. ; alar expanse about 2 mm. 



In D. silvestrii, sp. n., the club is broader and as long as the 5 preceding funicular 

 joints and half of the sixth together. In D. elegans the club is narrower and as long as 

 the 4 preceding joints and half of the fifth. In silvestrii only the first normal funicular 

 joint is longer than wide, the rest being transverse, while in elegans the first 3 joints 

 are cylindrical. In silvestrii the thorax as a whole is much longer than the abdomen, 

 whilst in elegans the two are equal. In the fore wings of silvestrii the fringe is long ; 

 there are 4 bristles below the submarginal distally, and the marginal plus the post- 

 marginal bears 4-5 bristles besides the long apical one. In elegans the fringe is short, 

 22 bristles below the sub-marginal vein and 8 bristles, plus an apical stronger one, 

 along the margin. In the mid-legs of silvestrii the tibia has an apical comb of 6 spines ; 

 on the first tarsal joint are 3 pairs of short thick plantar spines, whilst at the apices 

 of joints 2-4 are 1-2 similar spines. In elegans the tibial comb consists of 10 peg-like 

 spines ; there are 8 pairs on the first tarsal joint and 4-5 spines on joints 2-4 apically. 



