140 BEITISH LEPIDOPTERA. 



alga? " (April 26th, 1899). Triangular, with somewhat rounded 

 edges, pointed at both ends, grey in colour, covered with small grains 

 of sand ; one sent by Heinemann variegated with yellow particles of 

 lichen (Zeller). The case grey, with particles of dust worked into a 

 dense coating of silk ; bluntly triangular, almost like that of S. tri- 

 quetrella (Fischer). Bruand notes the case as "so similar to that of 

 S. tabuldla ( = sepium) that it is easy to confound them at first sight." 

 That of N. monilifera, he says, is " only a little constricted at the 

 anterior end which makes it slightly pyriform." [This want of 

 appreciation of marked differences throws light on some of Bruand's 

 other comparisons.] Koch says that the case is two-edged, somewhat 

 vaulted above, 2"' long, made of particles of lichen unmixed with 

 other materials." 



Habits of larva. — The larva is found less on fences than on tree- 

 trunks ; it is most difficult to breed, being restless in confinement, and 

 trying its utmost to escape. When short of food the larva? will eat each 

 other's cases completely (Koch). Bacot observes that the larva? were 

 noticed to come out of the posterior end of the case, and considered it 

 to be due to the shaking up that they had received in the post. The 

 larva drops on a thread readily, so that one might suppose the habit 

 of leaving the case a not unusual one. Griffiths notes that the close 

 similarity of the larva-cases to the patches of lichen (arising, of course, 

 from small particles of the latter being worked into the fabric of the 

 cases), made the larva? difficult of detection, especially as none of them 

 seemed to be in motion. A very favourite resting-place appeared to 

 be some narrow crack or crevice in the limestone ; in this the larva- 

 case hangs pendent. He considers that this sluggish habit, however, 

 " may have been caused by the boisterous east wind sweeping down the 

 Cheddar gorge " on the occasion of his first visit (May 6th, 1899), Avhich 

 frequently bore away into space the cases as he loosened them from 

 their attachment to the rock. Griffiths further notes that although 

 he did not see the larva? on the move during the daylight in a state of 

 nature, yet, in captivity, they seemed to wander round the box in which 

 they were confined, both at night and in the early morning. 



Larva. — The larva is grub-like with a large bulky abdomen and 

 small weak head and thorax. Head and prothorax black and glossy, 

 meso- and metathorax with dark brown corneous dorsal plates. 

 Abdomen bright yellow ; anal segment with a dark brown corneous 

 plate. Head rounded, black, glossy, not large, carried rather flat 

 (horizontal), retractile to a considerable extent, the loose whitish skin 

 in front of prothorax conspicuous. The prothorax rather long and 

 rounded (with somewhat of a neck or constriction between it and meso- 

 thorax), dark brown, chitinous, and glazed, the chitinous plate not so 

 completely covering the segment as in the higher Psychids. The meso- 

 thorax has a dorsal corneous plate, two lateral plates, one on either 

 side, the colour of plates paler brown than that on prothorax ; a narrow 

 white mediodorsal line commences at head and is continued over pro- 

 and mesothorax ; the metathorax (scarcely so well armed as the 1st 

 abdominal of Pachythelia villosella) has a small anterior dorsal plate, and 

 a larger and darker posterior one, on either side of mediodorsal area, a 

 rather small lateral plate is also present on this segment. The segments 

 increase gradually in size from the prothorax to the 6th abdominal 

 segment, and decrease more rapidly from the 6th to the anus. The 



