OF THE HIND WINGS OF HYMENOPTEROUS INSECTS. 136 



cases losing the re-curve as they approach the apex of the wing), I shoukl, in ill-defined 

 cases, call any straight hook at the commencement of the distal a sub-basal hook. Thus 

 in Fterygophorus I should reckon three (fig. 8), although there is nothing but the form of 

 that nearest the distal, and the fact of the scars beginning nearer the base than is usual 

 with distal hooks, to separate them. 



Allanius scrophularius has 5, on the costal nerve, at wide intervals, nearer the distal hooks than the 

 base. 



Allantus (N. America) (fig. 1 a), 6 or 7. 



Tenthredo Nothus, 5 well-marked sub-basal hooks, beginning near the distal ; but the series is con- 

 tinued almost to the base in the form of a deflexed hair, with a large scar on the lower edge of 

 the costal nerve. The other hairs have not such " scars." 



Tenthredo viridis (fig. 9 a), 12. Hylotoma ustulata, 3. 



Tenthredo viridis} 2. Hylotoma femoralis, } 



Sciapteryx, 4. 



Cephus pygiruBus, 6, about midway between the base and the distal hooks. 



Xyphidria Dromedarius has 7 prominences (fig. 12 a), close to the base of the wing, on one of which 

 is a large sub-basal hook. Probably 6 others have fallen off. 



Fore IViugs. — The folding over of the lower margin of the fore wing, for the reception of 

 the hooks of the hind wing, varies much in different insects, in form, size, arrangement, 

 and in texture, that part of the wing often differing greatly from the rest of the membrane, 

 as in Pelecmus polycerato7% Avhere the principal roll is thick and dark, and thickly studded 

 with short stiff spines or hairs, while the membrane of the wing is clear and thin, having 

 large fine hairs at wide intervals. It is frequently serrated, or edged with short stiff hairs, 

 along the upper part ; sometimes it takes a second fold, when the serration usually ceases 

 (as in Astata Boo])s). 



In some insects, as in all the Tenthredinid^e which I have seen, in ScoUa, Mutilla, and 

 Stilbum, there is but one roll ; and in some (as Mutilla) it becomes very narrow, and 

 extends almost to the base of the wing. 



In Ves2)a the roll for the distal hooks is very broad, and doubled, and there is a second 

 and narrower roll, nearer to the base, for the sub-basal hooks. 



In Chlorion the roll is broad at the centre of the wing, diminishes and widens again as 

 it approaches the base, and there is a short broad turning up of the wing quite at the base. 



In Pimpla, Paniceus, TrypJion, Mesostenus, and Pelecimis there are two separate rolls. 



In Ophion two, or one prolonged roll. 



(Query. — Is it always a roll ?) 



XypJiidria Bromedarms has some hairs on the costa, near the base of the fore wing, much 

 resembUng in appearance the sub-basal hooks in the same part of the hind wing. 



The only genus of four-winged insects, not Hymenopterous, on the hind wings of which I 

 have observed a hook, is A^Ms '* (Tab. XVI. fig. 13 a). It is found in all the British species 

 of that genus' described by Mr. Walker, of which there are specimens mounted by him in 



* Mr. Westwood having suggested to Dr. Gray that the hook of the Aphides was figured and described by Messrs. 

 Ratzeburg and Curtis, he consulted their works, and has kindly furnished me with the following observations :— 

 " Ratzeburg, in his ' Die Forst-Insecten,' figures four species of Aphides in their various states, but he does not 



