20 W. WESCHE — THE LARVAL AND 



1. Pyretophorus costalis, Lav. 



Larva. 



In the mature larva, which from the smaller size of the plumes and the- 

 great amount of confervoid growth is, probably, a quiescent stage, the head is 

 very small in proportion to the thorax, but this condition is not maintained 

 through the various larval moults^ as in Dr. Graham's series there are four 

 different stages, which I shall describe separately, under the obvious character 

 of size : — 



Larv?e 3 mm., 4 J mm., and 6 mm. long. Those of the length of 3 mm. are 

 of two types : — 



Type I. — Head neavly as large as the small tliorax. 



Type II. — Head of usual Anopheline type, half the width of tJie tliorax. 



a. (Type I). 



Head nearly as large as the small thorax. Antennae without plume ; two- 

 spines are present at the end, and several hairs, one of which is branched 

 (PJ. YI, fig. 2). In one of the two specimens the antenna has a darker tip. 

 Eye large, with pigment spot behind. Brush very bushy ; the plumes on 

 the face are of feathered hairs ; the plume on the mandible shows promi- 

 nently at the base of the antenna?. The base of the head seen from above,, 

 shows a dark chitinous collar ; on the dorsum this is broken in the median 

 line. 



The thorax is scarcely differentiated, but is very hairy with large plumes 

 of feathered hairs. 



The first three segments of the abdomen bear feathered hairs laterally ;. 

 and on the dorsum paired pabnate hairs are present on the second to the- 

 seventh segments (PI. V, fig. 22). The combs seem homologous with the 

 rows of spines which form lateral supports to the rudimentary siphon ; in 

 this species they consist of a double row of spines, a short one in front and 

 a long one behind (PI. \\ fig. 20). 



The siphon may be said to be differentiated but is only membranous. 



The anal segment is long, with still longer hyaline papilla? ; there is a 

 dorsal plume of peculiar long branched hairs, and the ventral beard is strong,, 

 and springs from a bulb ; it also consists of long branched hairs (PI. Y,, 



fig. !'•')• 



Described from two larvse. 



t. (Type II). 



On these larvae, the antennse are without branched hairs or the branches are 

 very minute ; the eyes are very small, apparently only the pigment spot 

 remains ; the collar at the base of the head is very much broader ; the thorax 

 is subglobular and well marked ; the abdomen bears five pairs of pahnate- 

 hairs, similar in shape and size to those on type I. 



Described from three larva?. 



