( viii ) 



coloration — such, for example, as that exhibited by $ .1/. 

 alpicola. The sexes, as exhibited, were very clearly distinguish- 

 able, and there was not much tendency to gynandromorphism, 

 though of sixty or seventy specimens almost every $ showed 

 some signs of S coloration. 



A discussion of the relative preponderance of the sexes 

 in gynandromorphous forms followed, in which Canon Fowler, 

 Colonel SwiNFiOE, and the Rev. F. D. Morice joined. 



Mr. 0. E. Jansox exhibited a pair of Siephanocrates doherfyi, 

 Jord., a Goliath beetle discovered by the late W. Doherty in 

 the highlands of British East Africa. 



Dr. T. A. Chapman exhibited cocoons of a Limacodid moth 

 from La Plata, with empty pupa-cases of a dipterous parasite 

 of the genus Systropus, obtained from Herr Heyne, who 

 unfortunately had no imagines either of the moth or fly. 



Dr. Chapmax said : — " Herr Heyne was under the impression 

 the pupa-cases were those of the Limacodid moth. I mention 

 this, not as a reflection on Herr Heyne, who would no doubt 

 have recognized what they were, had he really examined them, 

 but as showing what a close resemblance there is between 

 the two pupa-cases ; I have placed with them some genuine 

 Limacodid cases, Avith their cocoons, to illustrate this. The 

 resemblance is, however, not merely of appearance, bvit 

 functional also. The moth-pupa, i. e. the moth itself inside 

 the pupa-case, almost certainly by inflating itself with air, to 

 secure greater size and a stiiiened epiderm as a basis of muscu- 

 lar action, exerts an end-to-end pressure within the cocoon, 

 and so forces off a lid. This lid is not prepared by the larva, 

 in any special sense ; the cocoon is brittle, and the form of the 

 cocoon makes this lid the easiest line of fracture under the 

 forces exerted. This is seen to be the case by the fracture 

 being somewhat irregular, and different in each cocoon, and 

 may be proved experimentally, as I will immediately mention. 

 The fracture is also determined at the precise line in which it 

 occurs, and the forces acting upon the cocoon are intensified 

 at one point, so as more easily to start the fracture, l)y the 

 sharp beak (or 'cocoon-opener') with which the pupa is 

 armed. This beak acts, not by cutting, but by bringing the 

 strain on the cocoon to a more definite form at one point. 



