444 Dr. R. J. Tillyard on 



SoXix^s, long, and okjtt/p, star) in connection with the chaetotaxy 

 of the larva of Psychopsis elexjans (Order Planipennia) ; that is to 

 say, it is a slender elongated pyramid with its apex at the point of 

 insertion, and ending distally in a smaller or larger number of slightly 

 projecting angles, so as to resemble a small star when viewed end-on. 

 The star-like appearance of the end view is, however, less noticeable 

 in the present larva than in Psychopsis, partly owing to the angles 

 being little prominent, and partly because the pyi'amids are mostly 

 only four- or five-sided. Some of the macrotrichia, on the abdomen 

 especially, are almost as tliick basally as distally, and the terminal 

 angles do not project more than as shown in Text-fig. 1,/. These 

 macrotrichia are evidently closely related in form to those of the larva 

 of Micropteryx, which have been called by Dr. Chapman bullae, and 

 differ from them chiefly in not being inflated into more or leas bladder- 

 like bodies. Both are to be regarded as stages in the evolution 

 of scales, the flattening of a dolichaster producing a narrow scale 

 with longitudinal striae, and the flattening of a bulla producing a 

 broader, oval scale, vv^ith similar but more numerous striae. It 

 should also be noted that the larva of Microp)ieryx carries ei(j1d rows 

 of bullae, whereas the larva of Sabatinca has only four roAvs of doli- 

 chasters. 



There does not appear to be any clear connection between the 

 chaetotaxal arrangement in the larvae of Micropterygidae and that 

 found in other Lepidopterous larvae, inclusive of the Hepialidae. 

 Bearing in mind the close comparison which can be made between 

 the typical chaetotaxy of a Lepidopterous larva and that to be 

 found in certain Planipennian and Mccopterous larvae, one would 

 be justified in assuming that, in this character, as in the general 

 shape and coloration of the larva, the Micropterygidae are highly 

 specialised in correlation with their mode of life as dwellers in masses 

 of moss or liverwort. The macrotrichia of the Sabatinca larva are 

 closely similar to the processes or spines observable on the liverworts 

 on which they feed, as IVIi". Philpott observed when watching the 

 living larva. Consequently it may be suggested that the right 

 food-plant for the larvae of Micropteryx will be found to be a species 

 of liverwort in which the processes more resemble the bullae of the 

 larva (although I do not know whether such species of liverwort do 

 actually occur in England). 



As in the case of the macrotrichia, the microtrichia of the larva are 

 highly specialised, being no longer visible as distinct microscopic 

 hairs, but having become completely flattened down on to the 

 cuticle, like some of the micrasters in Psychopsis larvae, and all more 

 or less conjoined together, so as to produce a fine polygonal ridging 

 of the cuticle. Towards the posterior margin of each segment, this 



