ACANTHOPSYCHE OPACELLA. 387 



the hairs are relatively longer in proportion to the size of the larva), 

 both on basal chitinous plates ; iii has a long seta with a large basal 

 plate ; iv and v are subspiracular (iv with a long, v with a short, seta), 

 both close together beneath spiracle (as in adult larvae of C. unicolor 

 and P. villosella) ; the extra chitinous plate on the 1st abdominal is 

 present as in larva of P. villosella. The gap between the dorsal and 

 lateral plates on meso- and metathoracic segments is distinct, as also 

 is the division of the dorsal plate on the mesothoracic ; a wide and 

 well marked suture on mediodorsal area divides this plate in two, the 

 suture is white, the two parts of the plates black ; the folds of loose 

 skin between the thoracic segments and between the head and pro- 

 thorax are quite marked (Bacot, May 14th, 1899). At the hybernating 

 stage (October 8th, 1899) the larva is just about 13mm. in length, 

 and about 3mm. in width (at the 3rd and 4th abdominal segments, 

 the 1st, 2nd, 5th, 6th, and 7th, being almost equally wide). It tapers 

 gradually to the head, and more abruptly from the 6th abdominal to 

 the bluntly rounded anus ; the segmental incisions are distinct and the 

 abdominal segments are faintly divided into two subsegments. The 

 head is small, rounded above, rather flat beneath, thin from dorsum 

 to venter; the prothorax long and narrow, the mesothorax as long but 

 it looks shorter owing to its greater girth, the metathorax is actually, 

 as well as relatively, shorter and broader. The abdominal segments 

 1-5 are of about equal length to metathorax, 6 and 7 are rather longer. 

 To the naked eye the head and thorax above look like polished ebony 

 (some paler brownish areas are noticeable on the head if a lens be 

 used) ; the dorsa of the abdominal segments are also black, but of a 

 duller and bluer tone, showing pale coloration at the intersegmental areas 

 when stretched. There is a sharp clear white mediodorsal line across 

 the pro- and mesothorax, and, with the aid of a hand lens, it may be 

 seen faintly continued over the metathorax as a dull greyish streak ; 

 there is also a subdorsal orange-red spot on each side of the prothoracic 

 segment, placed rather posteriorly. The lateral and ventral areas of the 

 abdomen are pale yellowish-white, whilst the unplated portions of the 

 lateral and ventral areas of the thorax are pale smoky. The spiracles 

 are most striking, oval, very large, dark brown in colour. The hairs on 

 the head and elsewhere are slender, pale brown in colour, the setae placed 

 in usual specialised Psychid position — i outside and small, ii inside 

 and longer, iii above spiracle long, iv and v subspiracular, both small, 

 v, however, smaller than iv. The prolegs are as in P. villosella, the 

 central depression is very marked, the skin is apparently horny, the 

 oval of hooks large and strong, 24 on ventral, and 19 on anal prolegs, 

 the hooks larger and bolder than on P. villosella; the anal prolegs 

 have a lunular piece of chitin within the hooks in place of the usual 

 pit. (Judging from memory this species appears to have better 

 developed prolegs than any other Psychid larva examined.) The 

 lateral ridge is large, but not greatly raised above surface. The true 

 legs are blackish above, pale below. The antenna are rather con- 

 spicuous, and the plates at base of hairs large and especially strongly 

 developed on abdominal segments 8-10, the 10th of course bears the 

 usual anal plate (Bacot. Described Oct. 8th, 1899). Hofmann describes 

 the adult larva as 8-10 lines long, the back dark brown, with single 

 warts and hairs, sides, belly, claspers, and the inner sides of the legs 

 dirty yellow. Head and outer side of the legs shining black. The 



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