256 THE CANADIAN ENTOMOLOGIST. 



(a) On oak, Manitou . .Antenna; 8-jointed, formula 3 (24) 18 (567). 



(b) On rose, Santa Fe'.. ti 8-jointed, m 38(12)45(67). 



(c) On rose, Manitou.. n 7-jointed, n 3 (24) (17) (56). 

 Later, I myself obtained the following results : — 



(b) On rose, Santa Fe . . Antennae 8-jointed, formula 4 (3 (28) (567). 



Joint 4 was a very little longer than 3. 

 (a) On oak, Manitou. . Antenn;e 7-jointed, formula (34) (21) 7 (56). 

 I asked Prof Gillette for more abundant material of the Manitou 

 forms, and he sent them in quantity, but even then I could reach no 

 certain conclusions. It apjiears, at all events, that the antenna", jiever 

 6-johited as in ribis and canadense, may have either 7 or 8 joints in the 

 same form. Further, that while the third joint is usually the longest (as 

 in quercitronis), 4 may be equal to it or even a little longer. In every 

 instance, 5, 6, 7 are the three shortest, but when there are only 7 joints, 

 7 will be longer than 5 or 6. The differences seen in the formula given 

 are not so important as might appear, for the slightest change in the 

 length of a joint may alter the formula where several joints are so nearly 

 of one length. 



In general appearance, these scales are much alike, and do not differ 

 in any marked degree from L. qicercitronis. In. fact, unsatisfactory as I 

 feel the conclusion to be, I see nothing for it but to call them all Z. 

 guercitronis, var., at least until further studies of the living insects in all 

 stages can be made. The differences between these quercitronis forms 

 and Fitchii will also have to be clearly made out. Here again, the antennie 

 will not assist us. I think Fitchii and quercitronis must surely be distinct; 

 but to think so is not to prove it — and the variability already observed in 

 these forms tlirows doubt on formerly-accepted marks of distinction. 

 The statements of Mr. Douglas regarding willow and rose species in 

 England are suggestive in this respect. 



It is much to be hoped that some of the Eastern and Canadian 

 entomologists will study the biology of these perplexing forms. It is 

 only by such means that we can arrive at sound conclusions. When 

 dried specimens are sent to me, 1 can point out how they differ, but am 

 left often in doubt as to how far the differences are specific, and how far 

 due to ordinary variability, or even to the direct influence of the environ- 

 ment. 



At Las Cruces, one day, I found a small Eulexanium on an 

 umbellifer — one specimen only. It looked different from anything I had 



