BIONOMICS AND DEVELOPMENT OF LYGOCERUS SP. 1238 
optera Aculeata, and among Terebrantia, to the parasitic 
Cynipidae. The discussion of the affinities of the group is 
outside the scope of this paper, but it should be pointed out 
that the larval form of this particular genus of Ceraphroninae 
differs from the Chaleid larvae described by Seurat (26), Imms 
(11), Embleton (6), &c., m several respects. As regards the 
tracheal system, the late openmg of the spiracle of the 
second segment is common to many larvae of the entomopha- 
gous Hymenoptera. On the other hand, the larva of Ly go- 
cerus is remarkable for the reduced number of abdominal 
spiracles, and the rudimentary nature of the stigmatic trunks 
of segments nine and ten, and differs from the Ichneumonidae 
and Braconidae studied by Seurat in the absence of anastomosis 
of the tracheal vessels of either side ; though as Lichtenstein 
and Picard (15) have shown for the Braconid, Sycosoter 
lavagnel, this is not an invariable character of the external 
feeding Braconidae. 
The reduction in the number of spiracles is carried still 
further in Platygaster. Marchal (18) figures four spiracles 
in Platygaster ornatus, the first between the first 
and second segments, and those succeeding on the third, fourth, 
and fifth. The spiracle of the fourth segment (the propodaeum 
of the imago) differs from the others in its larger size, and the 
greater proliferation of the hypoderm cells surrounding it. 
‘Tl est pareil & une sorte d’histoblaste aux dépens duquel devra 
se former plus tard le grand stigmate du segment médiaire de 
Vadulte. Further, in Platygaster, the main tracheal 
trunks are not jomed posteriorly by acommissure. In Ly go- 
cerus a posterior commissure exists, and the spiracle of the 
fourth segment is indistinguishable from the rest. 
Likewise M‘Colloch (20) describes ‘ four or five pairs of well- 
developed spiracles’ in the larva of the Scelionid, Hu mi- 
crosoma benefica; but Ganin (8) states that there are 
nine spiracles in the third stage larva of the form of Plat y- 
gaster that he studied, and that spiracles are lacking only on 
the first, second, and three last seements. 
Kulagin (14) for Platygaster, and Ayers (2) for 
