24 The Developmental Characters of 



* Synonymic List,' and by Newman in his 'British Moths,' 

 api^ears to be most unnatural. 



It has often been asserted by Lepidopterists that no true 

 systematic arrangement can be founded on larval characters 

 alone, and this remark is to some extent correct, if we limit 

 our comparisons to the adult caterpillars only, so that objec- 

 tions might perhaps be legitimately raised from this point of 

 view to the suggested restoration of the older arrangement. 

 But the case is quite different if, instead of comparing the 

 adult larvae, we study their comparative ontogeny. By this 

 means, as explained in the previous part of this paper, we 

 may gain an insight into the true relationships of the species. 

 The first application of this principle to Lepidopterous larvae 

 was made by Professor Weismann, of Freiburg, in his 

 ' Studien zur Descendenz-Theorie ' (vol. ii., 1876), in which 

 work the author has studied the markings of the larvae of the 

 SphimjiihE in great detail from this point of view. The whole 

 subject is as yet almost in its infancy, and one of my chief 

 objects in bringing this paper before your notice is to 

 endeavour to convince you of the great necessity for paying 

 attention to the earlier stages of caterpillars. No group of 

 butterflies or moths has as yet been completely worked out 

 in the manner in which Weismann has investigated the 

 Sphingidm, and till this is done for the whole order we shall 

 never arrive at a truly natural classification. By making 

 careful drawings of caterpillars at every stage of growth — 

 using the microscope in the case of the youngest stages — all 

 who are given to larva breeding may contribute substantially 

 to the more scientific portions of our studies.^ 



1 shall now adduce evidence to show that the larvae of 

 most of the Bombyciform Noctuse are geometriform when 

 young ; the Geometriform Noctuae are, as will be remem- 

 bered, generally semi-loopers throughout life. 



Among the earliest observations in this country is a note 

 by Dr. Buchanan White (Ent. Mo. Mag., vol. v., 1869, 



2 The genus Acronycta specially claims to be thus worked out. See A. 

 G. Butler in Trans. Ent. Soc, 1879, p. 313. 



