Highland Insects. 131 



cate, flattened, beautifully reticulated, bright red Dictyopterus 

 Aurora, first discovered here, and not as yet found elsewhere 

 in Britain, where it has long been considered as one of the 

 arcana of science. It is very plentiful among rotten pine-chips 

 under logs, accompanied by its larva, which much resembles 

 that of the glow-worm, and, delicate as it is, is voracious enough, 

 for I found one feeding: on the carcase of a deceased " Shard- 

 born" beetle (Geotrupes) : the perfect insect may also be seen 

 flying feebly, towards evening, in the depth of the forest. Its 

 foreign brethren delight in settling on flowers ; but we have 

 only another species here, D. minutus, found very rarely in the 

 south, mostly in rotten wood. 



In consequence of the prevalence of fungoid growth under 

 the decaying bark of felled trees and stumps, the family of 

 Anisotomidm is well represented in the Black Wood by consi- 

 derable numbers of Liodes and Agathidium, the species of 

 which much affect such food. Three of our four species of the 

 former genus (one of them occurring here only) are indeed to 

 be taken in considerable numbers, gregariously haunting the 

 black powdery residuum of certain fungoid excrescences on 

 old bare pine stumps, in which they nestle, covering them- 

 selves as a sparrow does with road dust when water is not to be 

 had. They are very little creatures, and, like the Agathidia, 

 roll themselves up into balls, drop to the ground, and " scuttle" 

 off when alarmed by the approach of the collector's fingers. 



The Agathidia especially frequent a small dry, pink, puny 

 ball, growing on pine logs, and also damp, white layers of 

 fungus under bark. Although small, they are of great interest, 

 owing to their peculiarities of structure, not the least of which 

 is the diversity in the number of joints of the tarsi between the 

 two sexes. One species, A. 'Rhinoceros (Sharp), recently found 

 here, and apparently new to science, is conspicuous from the 

 great development of a sharp curved horn springing out of the 

 left mandible of the full-grown males. In small examples of 

 that sex the horn is much reduced, sometimes even entirely 

 vanishing; and this reduction or absence of a strong sexual 

 development is often found in the Goleoptera, where the 

 most favourable conditions are required in many instances to 

 produce the perfection of the type form, and especially in wood- 

 feeding insects. So great, indeed, is the disparity frequently 

 between the two extreme phases, that authors have been 

 tempted to describe them as specifically distinct. The common 

 stag-beetle exhibits a good instance of the possibility of in- 

 crease of the sexual distinction of size of mandibles under 

 favourable circumstances, in its earlier stages ; as small male 

 specimens often occur with very stunted jaws, when reared 

 from willow, or stinted in proper food during the larval condi- 



