THE GENUS ACRONYCTA AND ITS ALLIES. 149 



species made something almost approaching a tent ; they never 

 appear to eat their cast skins. 



The full-grown larva is 36-41 mm. in length by about 6 mm. 

 in width, the colour is a velvety-black or very deep brown. It 

 is difficult, to me at least, to describe the colours of these larvae 

 where so much of the effect that one ascribes to colour, is 

 really due to texture. The velvety-black of menyanthidis wants 

 the richness that aiiricoma and alni exhibit, as if they were 

 clothed in the richest and finest tissues of silken velvet. Some 

 few are really black, and the lateral line of these is a pinken 

 red, making a much more handsome larva than the usual type, 

 which is of a dark blackish brown ; paler and less glossy 

 towards the incisions. The segments are rounded from incision 

 to incision, and full in the middle. 



The trapezoidal tubercles, the supra-spiracular, the sub- 

 spiracular, and the first ventral tubercles are all about equally 

 developed and form a ring round each segment, the posterior 

 trapezoidal being only slightly out of line behind the others. 

 Each has about 20 pale reddish-brown hairs nearly 2 mm. long, 

 but with several 5 to 6 mm. long and some 7 mm., the longest 

 being on 5th and 6th segments. When stretched out, the larva 

 is thickest about the gth and loth segments, tapering regularly 

 in each direction ; but when alarmed or sulky, it is thickest at 

 5 and 6 and 12, i.e., it has still some trace of the riiniicis form. 

 The tubercles themselves are dull black, the post-spiracular 

 exists, as evidenced by one or two hairs. Underneath, the 

 colour is paler, a deep rufous-brown. On the 2nd segment the 

 three dorsal tubercles are replaced by a black plate fringed with 

 hairs drooping over the head. The head is black and shining, 

 with labrum and palpi dark rufous. The spiracles are of a 

 shining creamy white, that on the 12th segment being the 

 largest. The red lateral line is on the level of the sub-spira- 

 cular tubercle, which interrupts it on each segment, the line 

 consists in fact of a series of wedge-shaped marks, two on each 

 segment, the narrow end being towards the tubercle, the 

 anterior mark sloping downwards towards the tubercle, its 

 broad end at the incision, being thus above the end of the other 

 wedge of the next segment, which also slopes somewhat ; 

 the posterior one includes a dark spot or depression ; 

 the line is dull and obscure, or even wanting, on segments 



2.3, I3-I4- 



The black var. has the lateral line carmine, and not brick-red 

 as in the typical form, just indeed as in the previous skin, and 



