OF WASHINGTON. 67 
lished between these veins and those of higher Hymenoptera, 
and particularly with other orders, I shall gladly adopt a better. 
Throughout the entire body structure great difficulty arises in ho- 
mologizing with other groups, and in this brief review of the ex- 
ternal anatomy and some of its variations I have not attempted to 
alter existing names, nor to suggest relationships, offering it sim- 
ply as a statement of form and variation which can, perhaps, be 
read to advantage by one commencing the study of the group. 
The Head. 
In comparison to the size of the body the head is large. Its 
anterior (dorsal) aspect varies from a broad oval to an elongate 
triangle with rounded superior angles. Its dorsal (posterior) 
aspect also varies from nearly parallelogrammatic, through oval, 
to subcordate. It is usually carried nearly at right-angles to the 
thorax, so that the face is anterior, the occiput posterior, and the 
vertex superior. In the Eurytomince and some others it slopes 
towards the pectus, but in other groups it has the opposite 
tendency towards bringing it into the same plane with the thorax. 
The occipital margin is sometimes sharp {Encyrtince) and 
sometimes rounded (Eupelmincz) . In Caratomus, Dalm., a 
curious modification of the usually regular ridge is seen ; a deep 
cleft occurs behind each eye, and on each side of the indentation 
is a marked prominence of the ridge. The face is sometimes 
strongly convex, and occasionally angulate at the middle or at 
the insertion of the antennas : usually, however, it is nearly flat. 
The antennal grooves are frequently entirely obsolete ; some- 
times, however, deep and strongly marked. With some genera 
they are parallel, with others approaching either before or behind, 
and with a median separating carina of varying strength. The 
clypeus is transverse, and is either smooth, rounded, or dentate. 
It usually covers the labrum, but sometimes, as in Encyrtus, 
the latter is very evident. The cpistoma is seldom distinguish- 
able. The cheeks are either rounded, straight, or compressed. 
They are frequently traversed by a suture, running from the eye 
to the base of the mandible, and this suture is always broadest 
next the eye. It is the sulcus genalis of Thomson. 
The eyes are large and protruding, usually round, sometimes 
verging upon the pyriform, occasionally pubescent, and again 
