146 PROr. W. H. JACKSON ON THE 



The same statement is true of Stn. populi, but a specimen in the Zeller collection \\\ the 

 British Museum and two specimens in my own possession are exceptions. In the 

 Stephens collection of " Metamorphoses " in the British Museum is a specimen of Cossus 

 lignvpercla with two depressions distinctly separated. Other specimens that I have seen 

 possess but one. Two specimens of Zeuzera cescuU in the same collection differ in a 

 similar way ; one has a single depression, the other a double. All examples of Cucullia 

 verbasci bred by myself, and they are many, have had but one depression ; the sole 

 example of C. scrophularice seen by me, and it is in the Stephens collection, has two. 

 In the same collection is a specimen of Thyatira trldens and another of Th. psl * ; the 

 former has a single depression, the latter a double. 



The external anatomical characters distinctive of sex in a chrysalis and above described 

 are very constant, so far as I have seen after many years of observation ; and whenever 

 it has been in my power to verify my own conclusions on the subject, no error of 

 determination has ever been detected. There is, of course, a certain amount of varia- 

 bility in minute details, but it is never of such a kind as to prevent the recognition of 

 the sex. Por some time j)ast I have been collecting instances of this variability in 

 JPieris hrassicce, and on a future occasion I may hope to figure them. 



The following table gives a list of the species examined. It relates only to the female. 

 From time to time single examples of individual species have come under observation of 

 which unfortunately no record has been kept. They all belonged, however, to the 

 Heterocera and to the type 4 b, infra. The numbers prefixed to the names indicate the 

 number of specimens seen by me, and wdiere no such number is given it is to be 

 understood that it has been very great indeed. The letters " B.M. " stand for 

 British Museum, i. e. the Natural History Museum, as it is now called, and figures 

 following these letters indicate the Museum number. " Z " stands for Zeller collection ; 

 " St " for the Stephens collection of Metamorphoses, both in the National collection. 

 I may here express my thanks to my friend Mr. Heron, of the Zoological Department of 

 the Natural History Museum, for his kind assistance, and to Mr. Doncaster, of the Strand, 

 who courteously permitted me to inspect his stock of pupa3. 



1. Pieris brassicce; P. rapce ; 3 P. napl; 1 Mindra cyaneus (Moore), from Ceylon, B.M. 83, .52. 



2. 137 Vanessa' lo; V. urticce ; 26 V. pnlychloros; 2 Papilio Alexanor, Z. ; 1 P. polytes, from N.W. 



India, B.M. 84, 38 ; 1 Ornithoptera aeacus, B.M. ; 1 O. {Papilio) minos, B.M. 

 8. 28 Papilio Machaon; 35 P. podalirius ; 1 P. inerope, from S. Africa, B.M. 78, 10; 20 Thais cerisyi ; 



3 Th. hypernuBstra, B.M. 

 4 a. With double apertures. 



5 Acherontia Atropos ; 1 Sphinx convolvuU, St.; 1 S. ligustri; 2 Deilephila euphorbia, St.; 



2 Choerocampa porceUus, St.; 52 Ch. elpenur; 1 Ch. alecto, from N.W. India, B.M. 84, 38; 



2 Ch. nerii, B.M., Z. ; 1 Sinerinthus ocellatus ; 3 Sin. populi ; 1 Protoparce mauritii, from Natal, 



B.M.; 1 Daphnis Horsfeldii, Java, from the Horsfield collection, B.M. ; 1 Cossus ligniperda, St.; 



1 Zeuzera cesculi, St. ; 1 Cucullia scrophularice, St.; 1 Thyatira {—Acrunyda) psi, Z.; 4 Nyssia 



sonaria. 



* These are the names given by Stephens ; the speoies are now assigned to the genus Acronycta. 



