﻿1870.] 263 



the one from the other. No doubt this confusion had arisen in part from my having 

 taken two or three figures at different times of solitary examples too far matured ; 

 recent experience having demonstrated that when they are full fed, or nearly ap- 

 proaching that condition, their distinctive characters have faded away, and their 

 identification is then hopeless. I have therefore thought that a description, of both. 

 cerago and silajo may be of use to some, who perhaps, like myself, have hitherto 

 been unable to distinguish the one larva from the other as they chanced to come 

 under notice. 



My sincere thanks are justly due for the kindness and liberality I experienced 

 on tbe 29th of April from Dr. P. Buchanan White, of Perth, and on May the 4th 

 from Mr. George Baker, of Derby, they having both sent me an abundant supply of 

 sallow catkins containing young larvse of both species ; and I may mention that 

 thenceforth these larvse all fed and throve well on sallow leaves, and the moths ap- 

 peared from the 30th of July to the 14th of August. 



In both species the body of the larva is cylindrical, having the segments plump 

 and deeply defined, and tapering a little anteriorly ; the head decidedly smaller 

 than the second segment ; the hinder segment tapering also, and the anal pro-legs 

 very close together beneath its extremity. 



The larva of cerago has on the upper-surface, as far as the black spiracles, a 

 ground colour of reddish-brown or purplish-brown, and beneath the spiracles a much 

 paler tint of the same ; the ventral surface pale greyish-violet with a slight tinge of 

 bluish-gi-een on the anterior segments ; the whole upper-surface is freckled with 

 dark brown excepting the segmental divisions, which, when stretched out, are seen 

 to be unfreckled, and of rather a violet tinge. 



The dorsal line when visible is pale brownish-ochi'eous, often obscured by the 

 two dark brown lines that enclose it, and these often run together in a dark brown 

 spot at the beginning of each segment, are lost in the middle, and re-appear at the 

 end ; for, on the middle of each segment is a diamond shape of dark brown composed 

 of thickly aggregated freckles : the sub-dorsal is a dark brown freckled line forming 

 the upper boundary of a broad side-band of dark freckles, extending to the 

 spiracles, which are situated on its lower edge; the sub-spiracular region, belly, and 

 legs, are faintly freckled with pale brown ; the head is dark brown, the second seg- 

 ment has a black velvety collar or plate rounded behind, on which the sub-dorsal 

 lines appear conspicuously whitish or pale ochreous, with sometimes a faint indica- 

 tion of a dorsal line on it ; the anal tip is often similarly marked ; the tubercular 

 dots are often distinctly visible on the back in three pairs on each segment (two 

 pairs being the usual allowance), scarcely paler than the ground colour, and ringed 

 with dark brown. 



When young, some larvse of this species are much darker, with the marks and 

 freckles almost black ; but, as they increase in size, they become paler. In short the 

 distinct series of diamond shapes down the back, and the broad dark band along the 

 sides, ai'e characters that effectually distinguish this species. 



The larva of silago, though of similar size, form, and general aspect of colouring, 

 yet, when closely scrutinized, presents to view a different design in the ornamenta- 

 tion. 



The freckling on the back extends on either side as far as the sub-dorsal region, 

 forming on each segment an irregular squarish shape, quite uniform in depth of 



