A SEXUAL CHARACTER IN SOME LEPIDOPTERA. 215 



Clemens was accepted by me in mj' paper upon the larvae and pupae of 

 this species in the 26th Report of the New York State Museum of Natural 

 History, pp. 114-116, and has also been followed by other writers. That the 

 two forms are indicative of sex, has since been denied,* and it is to be 

 presumed that the denials are based upon results obtained in rearing them 

 to their perfect form. The green-spotted larva ma)^, therefore, be ac- 

 cepted as a dimorphic form, comparatively rare in my own collections 

 and in the examples that have come under my observation. 



The young collector of insects learns very early the simple method of 

 determining the sexes of his Luna, Polyphemus, Promethea, and Cecro- 

 pia pupK, and of many other bombycid pupas, by observation of the com- 

 parative breadth of their antennal cases. 



A means by which the sex in the pupa? of the Sphingidce may be infalli- 

 blv named, was pointed out by me in the Proceedings of the Entomological 

 Society of Philadelphia^ 1864, v. 3, p. 654. I have since found the same 

 characters applicable to the A^octiiidce and to other Hetcroccra. 



Prof. C. \'. Riley, in the Trajisactions of the Academy of Science of St. 

 Louis, 1873, vol. 3, pp. 128-129, and in the 6th Annual Report of the State 

 Entomologist of Missouri, for 1873, 1874, PP- 131-132, has described and 

 figured sexual differences in the pupae of Protiuba yuccasella, consisting 

 mainly, in the greater length of the " dorsal projections " on the several 

 segments of the male, in the length of the last two segments as compared 

 with those of the female (its shorter nth and longer 12th), and in its less 

 rounded apex. He says: "Sexual distinctions are very rarely observable 

 in chrysalids ; but after I had learned to distinguish between them, I 

 could readily separate the sexes in this case, and my judgment was con- 

 firmed upon the issuing of the moths." 



A few years ago I discovered an interesting feature in the armature of 

 the species of Cossus, by which the sex may at once be determined. I 

 have hitherto withheld its publication, until I had studied others of our 

 spined pupaj and could illustrate this feature b}^ proper figures; but the 

 opportunity for this has not been found, and I accordingly defer no longer 

 calling attention to it, that the observations of others in possession of 

 more abundant material may supplement the few that have been made by 

 me. 



It is known to lepidopterists that most of the pupaj of the species of 

 moths which in their larval stage live in the interior of stems of plants 

 and trunks of trees (endophjles), are armed upon their abdominal seg- 

 ments with transverse rows of teeth or spines, by the aid of which, when 

 the\^ are in readiness for their final transformation, they gradually work 

 their wa)^ through the outer packing of their gallery and the bark, pro- 

 ject their anterior segments to at least one-third the entire pupal length 

 through the opening, and hold themselves securely during the eclosion 

 of the moth. 



* Whitney : Canadian Entomologist, April, 1876, v. 8, pp. 75-76. Grote : id., May, 1876, 

 p. 100. 



