87 
XI. Genus HOLCOCNEME Konow. 
Rolcocneme Konow. Deutsche Entom. Zeits. xxxiv, 1890, p. 232. 
Body large; clypeus emarginate at apex; claws bifid or with subapical tooth; 
head and thorax more or less punctured, but little shining ; stigma orate at base, 
acuminate at apex, black ; posterior tibiae and tarsi thickened, the former deeply 
channeled exteriorly; hypopygium of male emarginate at apex; sheaths of female 
small, thickened. — Konow. 
This genus seems to me to be of very doubtful standing. I have 
found no American representatives, and the European examples show 
a tendency toward the preceding form (Croesus) in the enlargement of 
the hind tibia3 and metatarsus. The chief distinguishing character 
of the genus is the grooving of the hind tibia? exteriorly, but this occurs 
to a greater or less extent in practically all Nematids. 
XII. Genus NEMATUS Jurine. 
Nematus Jurine. Nouv. M6th. Class. Hym., 1807, p. 59. 
The characteristics of this genus, as indicated by the table of genera 
and an examination of the principal European specimens referred to it 
by Konow, are as follows : 
Body robust; antennae slender, tapering; clypeus more or less emarginate; hind 
tibiae and tarsi simple; claws bifid; last ventral segment of the male emarginate at 
tip, not produced or pointed; eighth dorsal segment of male broadly, obtusely trun- 
cate at tip, not at all produced; sheath of female broad and thick and with the last 
dorsal segment greatly developed and constituting nearly half of the abdomen. 
Konow assigned to this genus the group of species represented by 
the European Nematus luteus Pz., abdominalis Pz., bilineatus Klug., 
and a few others. The very large and thickened sheath, with long 
bordering fringe of hairs and large, thick, acuminately pointed ovi- 
positor, together with the enormously developed lateral clasping por- 
tion of the last dorsal segment, at once distinguish this genus from all 
other Nematines. Nematus unicolor n. sp. is typical in the features in- 
dicated and exhibits a close relationship with N. luteus Pz. of Europe. 
It is the only undoubted representative of this genus as restricted 
occurring in this country. Of the three other American species, two 
(N. pergandei n. sp. and N. chloreus Norton) possess the peculiarities of 
sheath and ovipositor, but lack the unusual development of the last 
segment. The third (N. mexicanus Cameron) seems from the descrip- 
tion to be a true Nematus. 
The unusual development of ovipositor and adjoining parts in uni- 
color n. sp. and the European species would suggest some peculiarity 
of habit in ovipositing calling for such modification. Nothing in this 
direction seems to be indicated by the habits, so far as known, in the 
absence of direct observation on oviposition. The European species 
feed on Alnus, the larva? resting on the upper surface of the leaves, 
