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OF THE ANTENNvE OF INSECTS. 393 



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them. In the interior of the antennEB, underlying the organs, is found a lobulated 

 membranaceous mass (fig. 2 b), in whieh the extremities of the nerve lose themselves. 

 It is difficult to make out the precise structure of the mass ; but it seems composed of 

 a number of membranous sacculi. It occurs in a great number of insects, and princi- 

 pally, if not always, in those whose organs are not dilated into a distinct sac in the 

 antenna- wall. 



In Pygcera bucephala I have noticed a depression on each segment of the antenna, 

 similar to those observed in some Coleoptera. 



In the Ghost Moth (Hepialiis humuli) the organs are in appearance more like those of 

 the simple sort in the Diptera, and are dispersed over the whole antenna. The male and 

 female antennae and antennal organs are precisely alike ; and it may be stated, as a rule, 

 that those Moths which possess such an exquisite sense of smell as Orgyria antiqua have 

 the organs more developed in the male than in the female, but they do not seem to be 

 more numerous than in those Moths which are reputed to possess a more obtuse olfactory 

 power. 



In Anthocera loti (Burnet Moth) the organs may be easily detected, being very 

 distinctly placed in a sliglit depression between the cuticular projections covering that 

 part of the antenna in which they are situated. The elosing-in membrane is ii-rcgularly 

 circular, of a diameter of -^-^j^ inch, and has a small papilla in its centre (S. fig. 1 b, 

 fig. 2 b). Behind this is a bowl-shaped sac, which has projecting into it a small papilla 

 in the centre of its inner wall, probably where the nerve impinges. This is shown in 

 the section at S. fig. 2 a, while at c the hair-Uke cuticular projections are seen partly over- 

 hanging it. 



The antenna of Macroglossa stellatorum is peculiar in having one side of each segment 

 furnished with numerous rows of hau-s. In the centre of each facet may be seen sacs 

 (fig. 19 a). These hairs give a peculiar appearance to the antenna. They gradually 

 enlarge towards the exterior of each facet, and possess large roots or follicles. 



In Sphinx ligustri (Privet Hawkmoth), the organs are to be found from base to apex 

 on every segment, on one side only, and in considerable profusion ; and, so far as I can 

 make out, are on the same plan as in the Biu-net Moth. 



I have examined many specimens of foreign species of Tetrix of aU sizes, and find the 

 organs are on precisely the same plan, and as numerous, as in the Tetrix described in 

 my former paper. 



At U, I have drawn the antenna of Forjicula aimcularis (common Earwig). Fourteen 

 segments are found to possess the sacs ; from one to three on each, at the distal or outer 

 end, as in fig. \ aaa. Their shape may be seen in section at fig. 2 a ; their diameter at 

 the sui'face is about -ayoo inch. 



I have also examined the antennae of an Agrion : they possess a few (about three or 

 four) of the simple cells I mentioned as occurring in such a clear manner in Zibelhila, 

 while in the common May-fly {Ephemera dmrna) they exist in but a very rudimentary 

 condition. 



In the parasites also, the antennae are furnished with similar organs, as shown at V., 

 VOL. XXII. 3 r 



