78 Descriptions of Preparations. 



for a fuller vocabulary, Burmeister^s Manual of Entomology, 

 translated by W. E. Shuckard, chaps, ii. and iii. 



27. Imago of Death's-head Moth 



{Acherontia Atropos). 



The development of wings and the differentiation of the body 

 into three great heteronomous divisions, the head, the thorax, and 

 the abdomen, are the most prominent external points in which the 

 perfect insect differs from the imago. The scaly covering of the 

 body and wings, the great development of the eyes, the somewhat 

 smaller but still not inconsiderable relative increase of the size of 

 the antennae and of the legs, the replacement of the fused maxillae 

 and labium of the larva by a spiral sucking proboscis, and a labium 

 provided with large palpi, and the reduction of the actively 

 functional mandibles to purely rudimentary structures, are almost 

 equally obvious points of difference between the larva and the 

 imago of a Lepidopterous insect. The maxillary palps are, as in 

 many Hymenoptera, and unlike what we observe in Diptera, very 

 small as compared with the labial. The prothorax is much reduced 

 in size. When viewed from above, the dense covering of scales 

 having been removed, it has the appearance of a narrow ring, 

 whence its technical name of ' collar,' interposed between the head 

 in front and the largely developed mesothorax behind. The 

 pronotum carries laterally a pair of vesicular scales covered with 

 hairs, and known as ' patagia.'' They are characteristic of the 

 order, and distinct from the 'tegulae' or wing-covers, with which 

 they have been sometimes confounded, and which are carried by 

 the mesonotal praescutum, and though very largely developed in 

 the Lepidoptera, are not peculiar to them. 



As points of more or less classificatory importance, mostly with 

 reference to the differences observable as existing between the 

 diurnal and nocturnal Lepidoptera, may be noted, firstly, the ter- 

 mination of the multi-articulate antennae in a filament, not in a 

 club ; secondly, the existence of a ' retinacular' apparatus, whereby 

 a spinous outgrowth on the under surface of the base of the hinder 

 wing connects it with an annular ligament similarly developed on 

 the under side of the anterior wings ; and thirdly, the two pairs 

 of spurs on the inner side of the posterior tibiae. The family 



