u Family of the Hymenoptera Heterogyna. 263 



scape clavate, nearly as long as the flagellum, which is also clavate; the 

 terminal joint half as long as the scape, the intervening ones short and 

 subequal. 

 Mandibles sickle-shaped, serrated ? along their inner edge. IVestw. 

 Maxillary palpi short and two-jointed, the joints subglobose. Wesiw. 

 Labial palpi longer, also two-jointed, the joints subclavate. Westw, 

 Mentum subtrilobate in front. IVestw. 



Thorax oblong, much narrower than the head, with a deep transverse 

 suture separating the nieso- and metathorax, the latter with a 

 large circular spiracle at its bass above. Legs simple, thighs subclavate; 

 tibics slender at the base, increasing slightly towards the apex, where 

 they are all furnished with a simple calcar, which is somewhat dilated 

 at the base ; tarsi slender, longer than the tibiae, the terminal joints of 

 the anterior slightly dilated, all the terminal claws simple. 

 Abdomen elliptical; the basal segment quadrate convex, forming a peduncle, 

 and separated from the next by a deep incision ; the ventral portion 

 acutely produced, the following slightly constricted at their base, and 

 all exhibiting laterally a conspicuous spiracle; the terminal segment 

 abruptly truncated or subretuse at its apex, the dorsal portion armed 

 laterally with two minute spines, and the ventral with a single one. 

 It is here requisite that I should state my reasons for considering 

 the three following insects as probably the females of the genus 

 Labidus. In the absence of any observation relative to their habits, 

 my arguments must necessarily all be derived from structure ; and 

 deduced from this I still admit that there is one, and only one, point 

 that makes me waver in my supposition. Sexual discrepancies are 

 universal throughout the Heterogyna, for it is rarely the case that 

 the partners resemble each other, therefore those differences here 

 must not startle us. In the preliminary observations I have already 

 shown that the males, the only sex accurately known of the genera 

 of this family, possess characters found partially in the Solitary and 

 Social Heterogyna, but conjunctively nowhere excepting in them- 

 selves, and upon this I establish a claim for their constituting a 

 family intervening between both. In these apterous insects (Ty~ 

 phlopone) I can exhibit a similar combination, which consequently 

 proves that they necessarily belong also to this family. In the form 

 of the head they are most closely like the female Scleroderma*, 



♦ I am prepared to show from the analogy of one of the ThynnidcB^ of 

 which I have both sexes taken in copula^ (the female of which is the 

 Biamma ephippiger of Guerin, and the male a Rhagigaster of the same 

 author,) that Scleroderma belongs to the Solitary Heterogyna, and not to 

 the BethylidcB as supposed by Mr. Westwood in his Monograph, and that 

 the males he has described as belonging to them are certainly misplaced. 

 There is every probability that what is usually considered as the Myzine of 

 Latreille, but which is the Elis of Fabricius, are the true males of Scleroder- 

 nia, there being no European species of the genuine Mi/zine, which is the 



