Sept., 1907.] Cook : In Defense of Incisalia henrici. 127 



3. Henrici larvae in the third stage differ constantly from irus 

 larvae iu the third stage. 



4. Henrici larvae in the final stage differ constantly from iriis 

 larvfe in the final stage. 



5. Henrici chrysalids differ constantly from irus chrysalids. 



6. Henrici " breeds true " ; henrici d^ mates with henrici $ and 

 the progeny are henrici. 



7. Irus "breeds true"; irus cj" mates with irus ? and the 

 progeny are irus. 



Of these seven facts the first five were (or should have been) 

 known to Dr. Skinner before the publication of his views in the Ento- 

 mological News for April, for I communicated them to him early in 

 February. The letter was enclosed in an envelope with my address 

 printed in the upper left hand corner and has never been returned to 

 me by the postal authorities. Even under the charitable assumption 

 that this letter never reached its destination, Dr. Skinner can hardly 

 plead that the facts were unknown to him without laying himself open 

 to the charge of culpable ignorance of the literature of his subject, for 

 W. H. Edwards published the life-history of henrici more than twenty- 

 five years ago * and the life-history of irus appeared in the Canadian 

 Entomologist in i9o6.f 



Three hypotheses may be entertained in an endeavor to account 

 for Dr. Skinner's attitude : (A) he has ignored the above facts — in 

 which case his argument is unscientific, for it is surely unscientific to 

 suppress evidence that does not square with a preconceived notion ; 

 (B) he doubts the facts — which is discourteous as well as unscientific ; 

 or (C) he has chosen to interpret them otherwise than as establishing 

 the specific validity of Grote and Robinson's henrici — which is 

 merely absurd. 



NOTE BY THE EDITOR. (^ N(^-^V<s.v J 



The distinctness of these two Thec/a is proved on the adult char- 

 acters adduced by Professor Cook. The stigma of the male being 

 present in one and not in the other. This is, as Dr. Skinner says, a 

 secondary sexual character ; but it is of absolute specific value. It 

 has generally been used as of generic value, and the reason we agree 

 with Dr. Skinner that it should not be so used, is not because it is 

 variable or inconstant, which is not the case, but because as a matter 



*Papilio, I, 150-152, Oct., 1881. 



tVol. XXXVIII, No. 5 (May), p. 141 and No. 6 (June), p. 181. 



