84 THE ENTOMOLOGIST. 



possessed of this type of pupa. Since, however, it is the 

 limiting form in one line of pupal evolution, I think it is not 

 improbable that some other group of which I am ignorant may 

 have attained a similar structure. 



There can, however, be no question that these two peculiar 

 specializations, of the early larva and of the pupa, are unlikely 

 in the highest degree to occur together in any other group. It 

 is possible, but convergence in this way can hardly be expected 

 to produce an approach in two apparently independent and un- 

 related characters. 



I may mention that, except where I use the facts recorded 

 by the late Vactor Tousey Chambers, to which I refer below, I 

 have depended for my data entirely on my own observations, and 

 therefore have to leave alone a number of American and other 

 exotic genera. Their places are tolerably obvious from imaginal 

 characters which associate them with those genera which I have 

 specially examined, but I have thought it better to say nothing 

 about them, especially as space prevents my dealing in detail 

 even with the material I have. As, for example, though I refer 

 to only a few species of Gracilaria and Lithocolletis, I have 

 actually examined the young larva3 of a considerable number 

 of species, and the pupae of a very large proportion of our British 

 species. 



The earliest reference I can find to the peculiar structure of 

 the mouth parts of these larvae is in Stainton's collected papers 

 of Dr. Brackenridge Clemens.* Clemens seems to have noticed 

 them as early as 1857 in Phyllocnistis, and to have been aware 

 that they occurred in some Lithocolletis. 



Stainton made reference to them in connection with Phyllo- 

 cnistis in the ' Entomologist's Intelligencer' in 1860. 



In the seventies this knowledge was fairly common property, 

 and the facts had been more or less observed by many micro- 

 lepidopterists. I know that at this period my friend Dr. Wood, 

 of Tarrington, was familiar with the main facts, and we often 

 discussed the questions of their origin and significance, as we 

 did many others with reference to the Micro-Lepidoptera. My 

 knowledge of the Micros is in fact largely due to information 

 obtained in this way from Dr. Wood. 



No one apparently published anything on the subject before 

 Chambers's papers appeared in Psyche, in the ' Journal of 

 the Cincinnati Nat. Hist. Soc' and in the American 'Entomo- 

 logist ' in 1877 and following years. He worked the matter out 

 very fully and carefully, ascertained the genera in which this 

 structural modification occurred, and also, which is most im- 

 portant, that they did not occur in any others (so far as known). 

 There are some details in which his work is open to extension 



- These papers were originally published in the Pr. Ac. Nat. Sc. and 

 Pr. Ent. Soc. of Philadelphia. 



