598 ON THE GENUS DIPHLEBIA, 



stronr/Jy friqiirfraf, the laterals being about 2-5 mm. broad at 

 their greatest breadth, the median slightly narrower. The 

 last 3 mm. of each gill consist of an attenuated tail, carrying 

 some long irregular hairs. Colour a very dark brown. (Plate 

 xix., fig. 3). 



Hab. — Medlow, Blue Mountains, N.S.W. A unique speci- 

 men, taken November 13th, 1909. 



Larval Type: the above unique specimen is in my 

 collection. 



Description of Nym2)h of Diphlebia nymjjho'ides. (Plate xix., 



fig. 2). 



This nymph is so similar in general appearance to that of 

 D. lestoides, that it is only necessary to give the chief mea- 

 surements, and to indicate the specific differences. The 

 general colour is blackish above, dull-greyish beneath. This 

 is of interest, as the basaltic rocks at Rocky Creek are grey or 

 blackish, wiiile the sandstone of the Medlow Creek is brown. 

 Thus the colour of the larva approximates closely to that of 

 the rock it inhabits. The nymph is slightly smaller than that 

 of D. lestoides; total length 30-32 mm. Head somewhat nar- 

 rower, about 5 mm. wide. Antennce 5 mm., basal joint and 

 base of second joint spiny ; basal half of second joints and 

 bases and tips of joints 2-5 white, not black (Plate xix., 

 fig. 7). Thorax and abdomen very similar to those of D. les- 

 toides. Caudal [/ills slightly narrower; laterals 10 mm., 

 median 9 mm., with tails only 2 mm. long; shorter, thicker, 

 and hairier than in D. lestoides. Fore-legs mueh smaller than 

 in D. lestoides, the femur being 4 mm., and the tibia scarcely 

 5 mm. long. Upper surface of head and thorax strongly 

 pitted all over; abdomen slightly less pitted. 



A comparison of the tibia of the two species shews some 

 small differences. In D. nympho'ides (Plate xix., fig. 4) the 

 lateral lobes are not quite so long as in D. lestoides (my former 

 paper, fig. 2) ; and the innermost of the four teeth is not 

 pointed, but somewhat blunt and nodding ; the spines or 



