A' . Y 7 '() MOL GICA L CONTRIB UTIONS. 147 



sylvania by H. Strecker, Esq., in response to a request for the white 

 variety of E. egle" 



According to Dr. Packard, * " From the same brood of larvae Mr. 

 Shurtleff has raised both the typical form [of E. egle] and a white 

 variety, which agrees well with Dr. Fitch's description of Ilyphantria, 

 ooUa/ris" 



If it were shown, as it is not, that the variety raised by Mr. Shurt- 

 leff was identical with the H. collaris of Fitch, still it would fail to 

 prove specific identity of the two forms ; before this could be established 

 it would remain to be shown that the " brood of larvae," from which 

 they were obtained, was the product of a single deposition of eggs. 

 In the event, which may be presumed frequently to occur, of two 

 broods of congeneric larvae feeding simultaneously on the same plant, 

 the two might very easily become intermingled, and the liability to 

 mingle would be increased in species closely resembling one another. 

 Two such instances of association of larvae of different species, which 

 would seem to be explicable only through mistaken recognition of one 

 another, have come under my observation, as follows : 



In September, of 1869, I collected from a poplar (Populus tremu- 

 loides) at Bath, N. Y., two folded leaves filled with Ichthyura larvae, 

 to the number, probably, of sixty. From these I obtained, the fol- 

 lowing spring, nearly that number of Ichthyura inclusa Hlibn., 

 together with a single example of Ichthyura vau (Fitch), a species 

 which I had not previously met with, but which Dr. Fitch represents 

 as being more frequently taken in his vicinity than either albosigma 

 or Americana [inclusa']. It is quite different from inclusa, and the 

 two have not, I believe, been suspected of being the same. 



In the other parallel instance, a group of perhaps fifty full grown 

 larvae of Clisiocampa sylvatica Harr., was observed at rest on the 

 trunk of a maple tree in the door-yard of my residence at Schoharie, 

 and scattered among them were several of the larvae of C. Americana 

 Harr. At this time, numbers of this latter species were traveling 

 about on fences, walks and buildings, preparatory to their pupation. 

 From a company like either of the above, of forms with which we 

 were not familiar, distinct species might be presented to us, with a 

 claim for specific identity resting on the plausible ground of having 

 been reared " from the same brood of larvae." 



I learn from Mr. C. Y. Riley, that he has recently been breeding 

 E. collaris from the larva, and that he finds it to be very distinct 



* Proc. Ent. Soc. Pliil, 1864, III, p. 130. 



