192 Mr. Shuckard'a Monograph of the Dorylidaej 



videntur — Bquamularumdefectu8,(ala8alteriuB8exu8caducafl innuens) 

 ct meaothorax spiraculum iusigne, a structura Mutillarum aliena." 

 Having above shown that these supposed weighty arguments of St. 

 Pargeau are not valid, I think their corroboration must fall with 

 them ; for both of these genera have very distinct squamulse (or te- 

 gula) ; and the mesothoracic spiracle is also conspicuous in many of 

 the Mutillida, particularly bo in the few smooth and glabrous females 

 of the genus Mtttillu itself. 



It" it had been possible consistently to overrule the plausibility of 

 these being solitary insects from our previous ignorance of any that 

 might have been appropriately assigned to them as females, the ma- 

 jority" of the few arguments which I shall adduce in favour of their 

 constituting a separate family, and to intervene between the Social 

 Ants and the Mutill'uUe, would have helped to strengthen the sup- 

 posed connexion with the social tribes, which however I admit to be 

 only a very close affinity. They are these : 1st. The before-men- 

 tioned solitary recurrent nervure to the wings ; 2nd. The single 

 calcar to all the tibiae ; 3rd. The labrum closely shutting the oral 

 orifice and inclosing all the internal trophi ; 4th. The curtailed 

 structure of the palpi ; and 5th. The enormous size of the male ge- 

 nital organ. 



The first two circumstances evidently separate them from the Mu- 

 tillidce, which in all instances have two calcaria to the four posterior 

 legs, and two recurrent nervures to the superior wings, with the so- 

 litary exception before noticed ; but it is necessary to observe that 

 in Dorylus the insertion of the recurrent nervure is considerably 

 further in advance towards the second submarginal cell than it ever 

 occurs in any of the Social Heterogyna that have but two submar- 

 ginal cells. The closing of the labrum is found frequently amongst 

 the Social Ants, but it also occurs in the Solitary Heterogyna in the 

 female Thynnida, : the fourth instance peculiarly separates them from 

 both tribes ; but in the fifth, the structure of the male organ, they ex- 

 clusively resemble several of the Solitary Heterogyna, for this is evi- 

 dently both in form and size a prehensile organ, and we know that 

 it is used as such in the males of several of the genera of these soli- 

 tary insects who thus seize and carry off their females ; and W. S. 

 MacLeay, Esq. has recently informed me in a letter from Sydney, 

 New South Wales, that this is universally the case in the New Hol- 

 land Thynnidae, and we consequently find, where this is the case, that 

 the male is much the largest insect- This last observation is not 

 limited to these families, for it is confirmed in the genera Anthidium 

 and Atilhophora, amongst the Bees, both of which carry of)' their fe- 



