THE CANADIAN ENTOMOLOGIST. 253 



to agree with the structure of the true cerussata, but was later found to 

 agree closely with that of my thalictri^ which he considers a proof that 

 ///^//V/r/, Lyman, and /r^'/V/tz, Smith, are identical. I may say that in 

 examining Dr. Smith's specimens before publishing my description of 

 ihalictrt, I recognized a specimen of that form standing among his speci- 

 mens of ceriissata, but I may be permitted to point out that while these 

 two figures, 25 and 26, are similar, they are still distinctly different, and 



were regarded by Dr. Smith as representing distinct species. 



In reference to the great similarity of ^<?;7/^5^i/^ and //^<z//V//-/ which 

 deceived Dr. Smith, I may mention that perfect bred specimens of the 

 latter, some of which were afterwards used by me as types, were sub- 

 mitted by me and other Canadian entomologists to Mr. Bird, and in 

 every case- were pronounced by him cenissata " without any doubt," and 

 that this opinion was maintained by him till I proved their distinctness. 

 In view of these facts, his statement that "their resemblance to cetussata 

 is striking for a species whose larvae differ so obviously, and it is likely 

 that flown examples of the one could easily be mistaken for the other," is, 

 to say the least, refreshing in midsummer weather. 



Mr. Bird's contention that M \2iX. perobsoleta diwd frigida are identical 

 there is no need of the name thalictri for the white marked form, I con- 

 sider absurd. The cases he brings forward of the differences between 

 specimens of speciosissima^ Hari'isii^ i7iqiicesita and pii7-purifascia are in 

 no sense parallel, as those differences are so slight as not to deceive any- 

 one, and intergrades also exist, while no one who did not know that 

 thalictri d.v\6. perobsoleta belonged to the same species would nave had 

 any hesitation in describing them as distinct, and as far as known no 

 intergrades exist, the case being exactly parallel to that of nitela and 

 nebris, as Mr. Bird has aduiitted in correspondence. As long, therefore, 

 as the names 7iitela and iiebris both stand, so long will thalictri stand for 

 the form to which I applied it. Dr. Fletcher having submitted to Sir 

 George Hampson two specimens from Manitoba which he thought might 

 be the true frigida, Sir George^ on comparing them with a coloured 

 drawing of the type of frigida, pronounced them the same, and quite 

 distinct from thalictri. Being extremely interested in the matter, I made 

 a trip to Washington, primarily to settle this question, taking with me 

 types of thalictri d^Vidi v-^x. perobsoleta and the best one of Dr. Fletcher's 

 specimens. On the first glance I thought Sir George's determination 



