138 ENTOMOLOGICAL NEWS. [March, '08 



dermis and is usually directly evaginated to form the imaginal 

 organ.' Thus it is a comparatively easy step to the abnormal- 

 ity of a free, external wing-pad, whereas such a condition would 

 be much more abnormal with the enclosed type of the Neurop- 

 tera and Lepidoptera or the still more highly specialized 

 stalked type characteristic of the higher Diptera. 



Intermediate between the simple and the enclosed types is the 

 "recessed type" of Tower (the Corethra type of Gonin). As 

 defined by the former, here "the fundament is invaginated and 

 then evaginated, and so lies in a hollow niche in the hypoder- 

 mal wall, but opens broadly against the cuticula." This type 

 he found in the Scarakeidae among the Coleoptera while Weis- 

 mann, '66, had reported it for Corethra, Simulium, and other 

 nematocerous Diptera. Thus it is possible that specimens of 

 these forms may be found in which the buds are free on the 

 surface, though no such instances have been reported. 



As to the significance of the monstrosities under considera- 

 tion there have been advanced two views. 



According to the one interpretation the occurrence of the 

 external wing-pads in the larva is to be regarded as an in- 

 stance of atavism a harking-back to a period when the larva 

 bore wings. 



The second interpretation, that favored by Heymons, is that 

 in these cases we have illustration of anticipatory monstrosities. $ 

 a kind of premature development in which characters normally 

 present in the pupal state are present abnormally in the larva. 

 He supports this view by citing other abnormalities present in 

 his specimens. 



That the latter interpretation is the correct one is strongly 

 supported by Mr. Powell's specimen. The most striking evi- 

 dence is afforded by the fact that in addition to the usual lar- 



J This instance and several very striking cases of anticipatory mon- 

 strosities in lepidopterous larvze (prematurely developed imaginal 

 antennae, maxillae, and legs) have been very fully discussed by II. 

 J. Kolbe (Allg. Z. f. Ent., 1903, pp. 1-9, 25-30), who proposes for 

 the phenomenon the term "prothetaly," rcXos completion, 7rpo0ew to 

 run before. 



