Acrotomus | BRITISH ICHNEUMONS. 195 

tibiae and tarsi mainly infuscate. Radial nervure straight or slightly 
curved apically. Length, 7—8 mm. 
[The following description of 7. anceps, drawn direct from Stephens, 
will show it to be almost indubitably synonymous :— 
A black and flavous species, with the abdomen not red and the face 
entirely black. Head somewhat large and broad; mouth and palpi ful- 
vous, with mandibles apically black; labrum with two fulvous spots. 
Antennae somewhat short and stout, entirely deep black. ‘Thorax immacu- 
late black. Scutellum pale flavous, with a faint concolorous line below 
it. Abdomen elongate, clavate, nitidulous, pubescent and black with all 
the segments apically stramineous-margined, except the first which is 
whitish-marked on either side of the black apex. Legs fulvous with only 
the hind tarsi and tibiae infuscate, the latter basally rufescent. Wings 
ample and hyaline ; areolet irregular and petiolate. Length, 7 mm. 
“Taken near Hertford, in July” (Stephens). | 
The strikingly nitidulous and elongate black body, contrasting with the 
long, pale legs, renders it a conspicuous insect. This species has the 
basal segment narrow throughout; but I possess a specimen, apparently 
undescribed, with the first segment hardly longer than broad and its 
spiracles more prominent than in any Ichneumonid with which I am 
acquainted; the latter was taken by Mr. Philip de la Garde at Lydford in 
September, 1891. 
This species was originally described from Austria and is said by 
Holmgren to be commonest in marshy places. It is certainly rare with 
us and I have seen but asingle 9, captured by Piffard at Felden in Herts. 
“Taken in June in the vicinity of the metropolis” (Stephens); and again 
in 1873 at the end of October near Worcester (Bridg. Trans. Ent. Soc. 
1886, p. 364). 
2. ridibundus, Grav. 
Tryphon ridibundus, Gr. I. E. ii. 188,¢. Acrotomus ridibundus, Plank. 
Zeits. Hym.-Dip. 1906, p. 219. 
A pubescent, black species. Mouth, clypeus, genal and two large facial 
marks, flavous. Callosities before and lines beneath radices flavous. 
Scutellum apically, and postscutellum transversely, flavous. Abdomen 
nitidulous and impunctate with the segments, especially the transverse 
second and third, apically flavous-margined; suture of second and third 
segments constricted. Anterior legs, posterior trochanters and base of 
the stout, infuscate hind tibiae, flavous; anterior femora infuscate beneath ; 
hind coxae and femora black. Wings with radix and tegulae flavous, 
stigma infuscate and areolet irregularly subpetiolate. Length, 7 mm. 
Differs from A. a/acer in its apically broadly pale second and third seg- 
ments, and entirely pale face; the anus is also impunctate. 
It was first recorded from Britain, | know not upon what grounds, by 
Marshall in 1870; its author knew but a couple of ¢ ¢ from Silesia and 
Strobl is the only person who has subsequently mentioned (Ichn. Stier- 
marks) this species, till Pfankuch found its true position in 1906. 
