26o BRITISH ICHNEUMONS. [Mesosfenus. 



I. ligator, Grav. 



Bassus zo/ia/or, Fab. Piez. 97, 6 (?). Mesosleiius ligator, i\x. I. E. ii. 760 ; Ratz. 

 Ichn. d. Forst. i. 147 ; Tasch. Zeits. Ges. Nat. 1865, p. in ; Thorns. O. E. v. 515 et 

 xxi. 2378 ; Voll. Pinac. pi. -xli. ft'. \ et 2, i ^ . 



Head of ? with cheeks sub-buccate, of $ with facial orbits, a man- 

 dibular and sometimes a clypeal mark, white. Antennae of $, setaceous, 

 of $ centrally white above. Thorax and scutellum immaculate ; meta- 

 thorax scabrous, apophyses obtuse, spiracles linear. Abdomen of 9 a 

 little compressed laterally and as broad as, of $ narrower than, the thorax 

 and oblong-ovate ; red or castaneous, with petiole and apical segments 

 black, the sixth to eighth laterally or apically white-margined ; post-petiole 

 stout, sub-quadrate, with prominent spiracles, of $ trifoveolate ; basal seg- 

 ments distinctly punctate ; terebra deflexed and a little longer than half 

 the abdomen. Legs elongate, red ; trochanters, coxae, hind tibiae, part 

 of their tarsi and in $ usually their femora towards the base, black ; hind 

 tarsi centrally white in $ and often ferrugineous in ? . Wings somewhat 

 clouded ; stigma, radix and tegulae infuscate. Length, io~i2 mm. 



This species is rendered abundantly distinct by its sub-depressed 

 clypeus, the female's falcately deflexed terebra and trifoveolate petiole, and 

 the male's apically white-margined anal segments. 



It occurs in June upon umbelliferous flowers throughout the Continent, 

 where it has been bred from Bombyx neustria (Grav.), Acroftycta rufnicis 

 (Laboul.), Zygaena irifolii and Cimbex amerinae (Brisch.). In Britain it 

 is certainly not rare, though only recorded from Essex by Harwood, who 

 found it at Wivenhoe in June, 1900. Piffard has given me specimens 

 from Felden in Herts. ; Thornley from Linwood in Lines., in June ; and 

 Connold has found it in the neighbourhood of Hastings. 



2. obnoxius, Grav. 



Mesostenus obnoxius, Gr. I. E. ii. 763 ; Tasch. Zeits. Ges. Nat. 1865, p. in, i ? 

 (nee Voll. Pinac. pi. xli. fig. 4) ; cf. Entom. 1880, p. 18 et Thorns. O. E. xxi. 2379. 



Head black with clypeus convex, sub-tuberculiform ; facial orbits of $ 

 rarely white. Antennae black, of $ somewhat slender and centrally 

 white-banded, of $ stouter and immaculate. Thorax punctate ; notauli 

 short, not reaching to the centre of the mesonotum ; apophyses acute, 

 spiracles oblong. Scutellum black. Abdomen convex and elongate- 

 ovate, broader in $ ; black with segments two to four, apical margin of 

 first and base of fifth, castaneous-red ; anus immaculate ; post-petiole 

 gradually dilated ; terebra less than half the length of the abdomen and 

 hardly curved. Legs slender and elongate ; black, with anterior except 

 coxae and trochanters, and the femora towards their base, red ; tarsi infus- 

 cate, hind ones of S centrally white. Wings normal, somewhat clouded ; 

 stigma, radix and tegulae black. Length, 10-12 mm. 



Bridgman (Entom. 1880, p. 18) points out the variation of the male; its 

 areolet may be more or less broad, sometimes very narrow, and the outer 



