Miscellaneous. 255 



fact that many of the skins of Typlilocyha presented a sort of appen- 

 dage inserted at the upper part of the abdomen, and at the first 

 glance producing an appearance as if the abdomeu had been bifur- 

 cated from its origin. 



This year, towards the end of Juno, the horse-chestnuts were 

 again covered with TyiMocybae, and I was able to convince myself 

 that we had to do not with an Entomophthorem but with an animal 

 parasite, a Hymenopterous larva tlie mode of life of which is very 

 remarkable. Almost all the TypJdocyhce collected on the trunks of 

 the trees bear, either to the right or left of the abdomen, a sac, of 

 which the length and breadth are equal, or nearly so, to those of 

 the abdomen itself. Concealed beneath the wings of the Homo- 

 pteran, the flight of which it scarcely affects, this sac is inserted in 

 the dorsal part of the second somite of the abdomen. A chitinous 

 thickening in the shape of a V, or, rather, of a reversed circumflex 

 accent, marks on the dorsal surface the point of insertion df the 

 sac. In the interior we find a Hymenopterous larva beut upon 

 itself ventrally in such a way that the mouth and the posterior 

 extremity oi the bodjr meet towards the point of suspension. The 

 two parts of the larva are separated from each other by a longitu- 

 dinal partition which divides the sac into two portions in communi- 

 cation at the two ends, A narrow fissure, the margins and the pos- 

 terior part of which are tinged with a blackish pigment, starts from 

 the point of the chitinous V and extends longitudinally for a dis- 

 tance equal to the length of a somite of the Typldocyha. When the 

 larva is mature this fissure is extended to the free exti'emity of the 

 sac, and by means of this kind of dehiscence the parasite is set free 

 and falls either into the crevices of the bark or to the ground, where 

 it speedily becomes transformed into a pupa within a coarse case, 

 like that of some Braconidae. 



The larva greatly resembles that of the Torymidae and especially 

 of the genus Misocampus. Upon each segment it bears a transverse 

 row of long stifi' hairs ; the mandibles are well developed. The 

 digestive canal is rudimentary and there is no anus ; the fatty bodies 

 are very voluminous and filled with rectangular crystals belonging 

 to the right prismatic system with a rectangular base. In a few 

 days I hope to obtain the perfect insect and thus to arrive at a more 

 precise determination of the parasite. But it seemed to me to be 

 useful at once to call attention to this first-known example of a true 

 animal-gall produced on the exterior of an Arthropod by another 

 Arthropod. The sac of the Typldocyha is, in fact, the extreme case 

 of a series of deformations, such as those caused in certain Hyme- 

 noptera by StyIop)s, or in the Decapod Crustacea by the Bopyridaj. 

 It may also be compared with the sacs also produced by hyper- 

 plasty of the cuticular hypodcrmis, but in the interior of the host, 

 by the Tachinidae (Ooyptera and Masicera) either in Heteroptera or 

 in Coleoptera, or, further, to the sac in which the Eutoniscidio live. 

 It is evident that the Typldocyhce were infested in the pupa- or even 

 in the larva-state, and it would be very interesting to follow the 

 development of the sac step by step. The physiological effects pro- 



