Bassus | BRITISH ICHNEUMONS. 81 

BASSUS, Fallén. 
Fall. Specim. Hym. (1813); Thoms. O. E. xiv (1890), p. 1465. 
Head with the cheeks short, clypeus apically emarginate centrally, face 
not smooth, mandibles stout and discally deplanate; ? with internal 
orbits, ¢ face entirely or mainly, white. Antennae not or hardly ex- 
tending beyond apex of thorax, with flagellum filiform and in @ slightly 
incrassate towards the apex, of ¢ with no elevated lines and 16—18 joints. 
Thorax white-marked, with notauli short but distinct, the metathorax 
areated and the spiracles at an appreciable distance from the lateral 
carinae. Abdomen not apically compressed; the anterior segments dis- 
tinctly impressed transversely, and somewhat strongly and subrugosely 
punctate; basal segment with discal carinae entire or at least extending 
to its centre. Legs not slender; hind tibiae broadly white centrally, and 
nigrescent at both extremities. Wings with no areolet and the submar- 
ginal nervure not approximating the second recurrent. 
The very distinctly transimpressed basal segments will at once dis- 
tinguis!: this genus from the remainder of the Zryphoninae and the allied 
Bassides. 
Table of Species. 
(6). 1. Anterior coxae entirely pale; abdo- 
men centrally red. 
(5). 2. All the coxae pale. 
(4). 3- Abdomen broadly red; hind tibiae 
tricolored .. . + .. I. LAETATORIUS, Fad. 
(3). 4. Abdomen not or hardly red; hind 
tibiae bicoloured = = 
(2). 5. Hind coxae basally black; central 
segments red-banded .. x 
(1). 6. Antenor coxae not entirely pale; ab- 
domen rarely red-marked. 
(8). 7. Hind coxae red; basal segment apic- 
ally pure white fs A a 
(7). 8. All the coxae black ; basal segment 
- not white-marked. 
(10). 9. Apices of hind tibiae black; 2 epis- 
toma white-marked Be .. 5. VARIICOXA, 7homes. 
(9). 10. Apices of hind tibiae ferrugineous ; 
2 epistoma immaculate . ; 
. TRICINCTUS, Graz. 
ty 
. MULTICOLOR, Grav. 
Os 
4. ALBOSIGNATUS, Grav. 
On 
. ANNULATUS, Grav. 
winged. The same evening I further noticed Pollenia rudis, F., sucking the Aphids; the bush was 
then covered with flies, with Bassus lactatorius and other species of this genus, B. tricinctus 
being common. The same bush was again covered with this Aphis, both winged and apterous, 
on its new shoots on July, 29th, 1909. At 10.0 a.m. I saw a Syrphus corollae, Fab., ovipositing 
among them. She appeared to pay no especial attention to the position in which she placed the 
eggs, though in every case they were deposited on the leaf or stem of the plant amid the thickest 
masses of Aphids, usually pushing aside some immature Aphis to do so, in such a way that after 
deposition the egg was half concealed by the latter's body. The egg is subcylindrical, one mm. in 
length and rather more than a quarter mm. in breadth at its broadest point, which is slightly before 
the centre; its apex is entirely rounded and thicker than its base, which after curving inwards a 
little becomes truncate, as though abruptly cut off by contraction of the ovipositor. The colour is 
pure white and the surface is beautifully reticulate. Among the Aphids were also Hyetodesia basalis, 
Zett., and Poillenia rudis, F. On 2nd July the egg had become olive-green beneath its white shell 
and one streak showed light grass-green ; on 4th the stramineous, black-spined larva had emerged 
and was very active. 
G 
