EEAX. 205 



E. prolificus by the darker abdomen, with narrower grey hind margins of the segments ; 

 the longer ovipositor, the darker mystax, &c. 



N.B. — E. unicolor, Bell. (I have not seen the type, it is not in Bellardi's collection), 

 from Orizaba, Mexico, described from the female sex only, has a great deal in 

 common with the above-mentioned females. The keel-like elevation of the middle of 

 the thorax, described by Bellardi, is qnite conspicuous in my specimens ; the ovipositor, 

 as described by him, is long ; the whole appearance very hairy. But the other details of 

 Prof. Bellardi's description do not answer. 



Van der Wulp has specimens of both sexes of an insect from Guanajuato, Mexico, 

 which he refers to E. unicolor ; according to him, the male agrees with the female in 

 everything except the genitals (in other words, it has no silvery segments on the 

 abdomen'?): if this determination be correct, it justifies me in not identifying my 

 specimen with E. unicolor. 



10. Erax ? 



Hal. Mexico, Northern Sonora (Morrison). 



Very like E. prolificus in size, colouring, and in the structure of the male forceps. 

 The principal differences are : the male has nearly the whole of the abdomen silvery, the 

 segments 2-5 beset with silvery hairs which are parted in the middle and combed out- 

 wards, and the expansion of the costa larger and darker-coloured ; the female (or at 

 least the specimens which I refer as females to the above-mentioned males) has the 

 abdomen uniformly grey, beset with short whitish hairs, the ovipositor equal in length 

 to about five of the preceding segments, and therefore longer than in the preceding 

 species. In both sexes the femora are red on the upperside. Two males and three 

 females. 



11. Erax ? 



(?) Erax carinatus, Bell. Saggio &c. ii. p. 36, t. 2. f . 9 \ 

 Hah. Mexico (Truqui l ), Presidio (Forrer). 



Belongs to the same group as E. prolificus and Erax Nos. 9 and 10, e. g. with a crested 

 thorax. I have two females which cannot be referred to either of those species. The 

 femora are red above, and dark metallic green on the underside only, and in this 

 respect this species is like No. 10 ; it has the same long ovipositor, equal to about five 

 of the preceding segments united. But the abdominal segments are much darker 

 in the middle than on the sides, and not uniformly grey ; the wings are shorter and 

 more brownish ; the hairs on the scutellum and on the prsescutellar space are not 

 white, but dingy yellowish. I suspect that this may be the female of E. carinatus, 

 Bellardi, of which the male only is described ; I obtained this impression on com- 

 paring the male in Turin. 



