126 MISS STAVELEY ON THE NEURATION 



very deceptive ; each observation liad, therefore, to be repeated many times to ensure 

 accuracy. 



The sketches accompanying this paper were (with the exception of two or three which were 

 traced from the wings themselves) made Tvith the camera lucida, aided by the compound 

 microscope or a simple lens ; and this may excuse any artistic defects that they exhibit. 



The hooks on the front margin of the hind wings of the Hymenoptera may be divided into 

 two groups : those placed near the middle of the front edge, which may be called the 

 Distal hooks, and which appear to occur in the wings of all Hymenopterous insects ; and 

 those situated nearer to the base of the wing, which have been called the Sub-basal hooks. 

 "^I'hen the latter are present, they are in general quite distinct from the distal series ; but 

 in some few insects the two series seem gradually to pass into each other*. 



The disposition, form, and number of these hooks appear to afford, not only good 

 characters for the separation of very nearly allied species, such as the species of the genus 

 OpMon, but to afford also excellent characters for the distinction of genera and families ; 

 and I have little doubt that when more attention sliall have been paid to them, their 

 importance in the economy of the animals will be fully established. 



Mr. Frederick Smith, in the notice before referred to, expressed his belief that the hooks 

 Avould be found to be more developed in those insects which have the quickest flight ; but 

 further examination has not confirmed this opinion, as one or two of the insects marked 

 by him as of very quick flight (as Astata Boops) have the hooks slightly developed and 

 few in number. 



The neuration of the hind wings is somewhat similar to that of the fore Tidngs, and 

 presents variations which fall naturally into three groups, according to the form of the 

 front or costal nerA*e. 



I. Costal nerve divided near the base. 

 A. Upper branch of the costal nerve marginal at least to the centre of the wing, where 

 the upper and lower divisions are re-joined. 

 Vespid^. "^ 



Vespa maculata 



Polistes (4 species), fig. 43 



Polybia, fig. 44 . 



EUMENID^. 



Eumenes 



Synagris 



Costal nerve branching at the re-junction. 

 Distal hooks commencing on the re-junction. 



* These hooks are only thus hriefly mentioned by Mr. Westwood in his ' Modern Classification of Insects' : — 

 " Another character of the order (Hymenoptera) consists in the counexiou, during flight, of the two wiugs on each 

 side of the body by means of a series of minute hooks, along the anterior margin of the posterior wings, which catch 

 the hinder margin of the anterior wings, thus producing one continuous surface on each side." (Vol. ii. pp. 7Q, 77 ■) 



Dr. Gray has kindly sent me the following observations : — " I do not find that Mr. Westwood anywhere makes use 

 of the hooks in the classification of the insects ; and in Curtis's ' British Entomology,' where the wings of the different 

 genera are often figured in considerable detail, I do not find a single instance in which the hooks are either figured or 

 noticed. I have inquired of Mr. Walker if he had ever.made use of the hooks on the wings of Hymenopterous insects to 

 distinguish either the genera or the species of these insects, or if he could refer rae to any author who had done so ; 

 and he said he had not himself, and, after searching in several works where he thought they might have been so used, 

 he was not able to refer me to any." 



