CHARLES T. BRUES. 



in the Papilionids and some Satyrids almost globular; in the 

 Pierids, long, slender and spindle-shaped; in the Xymphalids, 

 somewhat barrel-shaped with projecting ribs reaching from base 

 to apex, etc. In some butterfly eggs there is a well marked lid, 

 defined by a weakened line in the shell, along which the shell 

 ruptures on hatching, causing the lid to separate from the re- 

 mainder of the shell. In the Hemipterous family Pentatomidae 

 a similar lid occurs, along the margin of which is a circle of spines 

 or thorns. When the eggs of insects are better known, they will 

 undoubtedly prove of great interest from a taxonomic stand- 

 point. Incidentally, it is of more than passing interest to note 

 that these organisms in such an early stage of ontogeny show 

 visible external characters by which not only larger groups may 

 be delimited, but which serve to distinguish the numerous species 

 of some groups. In this connection, it must not be forgotten, 

 however, that the egg-shell is really formed by the mother and 

 is hence a direct product of the adult insect and not of the embryo, 

 so that its high specialization cannot be attributed to any dif- 

 ferentiation of the embryo. In this sense we are dealing with a 

 matter of entirely different significance from that now to be 

 presented in relation to insect larvae. 



Insect larva? may be separated into several rather clearly 

 defined types, and in at least one of the extensive orders, the 

 larva> of the great majority of the species included may be re- 

 ferred to a single, quite consistent type. Without question t In- 

 most primitive of these is the campodeiform larvae so named in 

 recognition ol its similarity to the imago of Campodea, a genus 

 of Apterygote insects. Campodeiform larvae appear with many 

 modifications in several widely separated orders of insects. A 

 second, quite consistent type, is caterpillar-like or eruciform, and 

 larvae of this kind prevail almost universally in the Panoi p.it.f 

 and several orders which appear to have been derived from a 

 Panorpate ancestral type. Various other types are also e.iMly 

 to be recognized, most of them of quite restricted occurrence 

 and characteristic habitus. A vast residuum are either highly 

 specialized in structure or greatly simplified through the loss of 

 appendages and the acquisition of a vermiform body. These 

 latter, so-called apodous larvie, although quite uniform in gross 



