14 THE CATERPILLARS OF NEW ENGLAND. 



this connection that Libytliea has four subscgnients as in the bulk of tlie 

 XyniphaHnae, altliough in this case the four subsegnients are of nearly 

 c(|ual size. In the remaining Xyniphalidac, that is, in the Satyrinae, we 

 find a decided difference, the front subscgnient only a little larger than the 

 rest or scarcely larger at all, and the whole segment diyided into six sub- 

 segments. A single exception only has been noted in the fifteen species that 

 I haye been able to examine, and that is in the European IIi[)parcliia liyper- 

 anthus, which has only four subsegnients, tlie front one no larger than the 

 others, while janira, placed next it by some European entomologists, has the 

 normal nunilxn". Closely agreeing with them are the Pierinae which usually 

 haye six subsegnients, but in the European A})oria tlie last two are hardly 

 separable. A curious exception howeyer is to be found in the Antlio- 

 charidi, which usually haye seyen subsegnients, including our own gcnutia, 

 though the European belia has but six subsegnients, and the species of 

 Zegris only fiye and the last two of these scarcely separable from each other. 

 In the lowest family Aye find a distinction between the Hesjieridi and the 

 Panii>hilidi in the o-reater numlier of subsetrments belonijinff to the latter 

 group. The Hesperidi usually haye fiye, the first of them the larger. 

 But our Ilesperia montiyagus has only four and the same is the case with 

 two s})ecies of Thanaos, persius and lucilius, while Thanaos juyenalis and 

 another unknown species agree completely Ayitli the bulk of the Hesperidi. 

 The Pain])liilidi on the other hand haye seyen subsegnients, though a 

 reniarkal)le exception ap})ears to occur in the European Ado})aea lineola, in 

 which the subsegnients behind the first appear to be paired, so that there 

 are here but three where ordinarily there are six. 



Finally a few words may be said regarding the glands haying their 

 external opening upon the surface of the body. These may be diyided, 

 perhaps naturally, into two groups, according as they occur upon the tho- 

 racic and abdominal segments. Thoracic glands are ap])arently found in 

 the caterpillars of all butterfiies though they are liest known, as they are the 

 most striking, in the caterpillars of the Papilioninae. Here they are 

 found on the dorsal surface, bear the name of osmateria, and consist of 

 a fork-shaped sac which, ordinarily drawn entirely within the body, may 

 be almost instantaneously thrust out through a transyerse slit in the first 

 thoracic seo;nient. This or<»aii A\'licn thus extruded is ofenerally of a brio'ht 

 color and exhales a more or less decided odor differing according to the 

 s[)ecies, being scarcely perceptible in Lacrtias and yarying through all 

 degrees of ofFensiveness to a truly sickening stench in Iphiclides. The con- 

 struction of this organ has been described in somewhat different terms by 

 Studer and Klemensiewicz. It is really a deyelopment of the integument 

 and the cells at its base are glandular, their secretion being perhaps dis- 

 charged through ])or('s of the adjoining cuticula. "It may be assumed," 

 says Dimmock, "that the odorous secretion accumulates in the inA'aginated 



