1865.] 213 



species of Tragus in my collection, including T. exesorms Brulle, nor 

 in any other Ichneumonidous species, so far as I have observed, except 

 Cri/pfiis robit^fus Cress, six 9 , ^"d an appai'ently undeseribed species 

 (one % one $ ) belonginc; to a new genus intermediate between Joppa 

 and Btirijceros, do I find any traces of this remarkable anomaly. The 

 above is the sum total of variation, as regards these "bullae," in 638 

 wings appertaining to 70 distinct species of Ichneumon ; and it appears 

 to be almost universally variation and not specific difference, because 

 there is but a single instance where a species, represented by over two 

 specimens, exhibits any given variation in both the front wings of all 

 the specimens. That instance is annulipcs'! Cress., a very variable 

 .species, of which I possess eight specimens, no two of them exactly 

 alike in their general coloration, and all eight of which have the bulla 

 A obsolete in both wings. In 319 specimens of any given species of 

 insect, we should be apt to find almost as great an amount of variation, 

 as that which has been detailed above, in any given specific colorational 

 character. And ^^et this particular type of bullfe is not a specific cha- 

 racter, but one which runs through 70 distinct species of a particular 

 genus ; and as already stated, remarkable modifications of the normal 

 bullae of Ichneumon are found in all the other Ichneumonidous senera 

 with which I am acquainted. 



Besides the seven spots which, as has been already shown, exist typi- 

 cally in the front wing of Ichneumonidse, there are usually in the hind 

 wing two buUas located on the lower or hindiuost end of the two prin- 

 cipal cro.ss-veins. But for the purpose which I have in view, it is un- 

 necessary to dwell upon this point. 



I might have insisted likewise on the very general, though not uni- 

 versal, persistence of the pale spot at the base of the stigma throughout 

 Ichneumonidse and Braconu/ee, and several other Hymenopterous fami- 

 lies; and, indeed, throughout certain families belonging to other Orders. 

 But as this character is perhaps partly structural, being connected with 

 the thinner organization of the stigma at that particular point, for cer- 

 tain unknown structural or functional purposes, I have forborne taking 

 any account of it. In the case of the bullae, however, we cannot rea- 

 sonably assume, that any structural or functional necessity could require 

 a wing-vein to become suddenly thinner at some particular point, and 

 then as suddenly become as thick as before ; for it has been proved 

 that the wing-veins are, properly speaking, veins, i. e. that they arc 

 fluid-conducting tubes. And even if we make some such gratuitous 

 assumption, this will not explain the white blotch on the membrane of 



