MORPHOLOGICAL ADAPTATION IN INSECTS — GRANDI 2O9 



are present in the thorax and abdomen. The development is 

 euholometabolic. 



In the very large family Curculionidae the larvae are, as is known, 

 apodous, and generally cyrtosomatic. Almost all, moreover, develop 

 endophytically ; therefore I have selected ectophytic or leaf-mining 

 forms. 



Among the open feeders (sensu lato) I have examined some Me- 

 cininae belonging to the genus Cioniis Clairv. {hortulanus Geoff r., 

 scrophulariae L., olens ¥.). The clearly ectophytic larvae of the first 

 two species do not exhibit, as was to be expected, very remarkable 

 features except the presence of pseudopodia in the first eight segments 

 and the fact that they cover their own bodies with a kind of liquid 

 protective cloak. But if we consider the larvae of the third species, 

 which have a somewhat specialized behavior, we may point out some 

 interesting facts. These larvae, even though really living ectophyti- 

 cally on the very woolly leaves of several Verhascum, have the odd 

 habit of excavating a kind of gallery in the woolliness, that is, a kind 

 of mine of a new type — actually, a pseudomine — and keeping the head 

 in the horizontal plane while shifting it sidewise and anteroposteriorly. 

 They exhibit some peculiar characteristics of the mining larvae : head 

 capsule flattened, hypognathous, but with a tendency to prognathism, 

 very much enlarged and furnished with two curious sublateral scle- 

 rites, which, joined as they are to the posterolateral edges of the dorsal 

 surface of the head capsule by means of a narrow membranula, take 

 the place of the laminar processes repeatedly mentioned in regard to 

 the mining larvae of several orders of insects. Moreover, on the ven- 

 tral face two conspicuous quadrangular expansions, joining tentorial 

 pons and hypostomal laminae, contribute to close the head capsule 

 before the foramen magnum. 



Among the leaf-mining Curculionidae we must consider the weevils 

 belonging to the genus Rhynchaenus Clairv., whose larvae bore 

 rather high and narrow laminar mines, at least in the first period of 

 their lives. They exhibit a body moderatly flattened ; head capsule 

 subprognathous, flattened, caudad prolonged by two dorsal lateral 

 plates attenuated abruptly in the distal part and here enlarged like a 

 club, between which a prolongation of the medial longitudinal apodeme 

 of the epicranium conspicuously juts like a rigid staff. On the lower 

 surface the hypostomal laminae, expanded in large plates which con- 

 verge almost to the point of meeting, tend in such a way to close the 

 head capsule before the foramen magnum. The cranial walls are 

 strengthened by strong apodemata; the integument of the antennae 

 and the maxillolabial complex is sclerotized. 



