44 
VIII. Genus PTERONUS Jurine. 
Jnrine, Nouvellc Methode do Classer les Hymenopteres et Pipteres, T. i, p. 61. 
Konow, Deutsche entoniologische Zeitschrift, xxxiv, 1890, Heft n, p. 237. 
Body large, hard; clypeus incised at tip; claws bifid; antenna' long, frequently 
pale beneath ; stigma usually unicolorous ; mesonotnm and mesoplenrse usually not 
or sparsely punctured; head subrotund ; labium not or slightly prominent; eighth 
dorsal abdominal segment of male subtriangular, produced at apex ; procidentia 
truncate at apex; hypopygium narrow at apex and subtruncately rounded; sheath 
of female small, narrow; apex never acuminate. 
The genus as characterized above by Konow is perhaps the largest in 
point of number of species of the several genera erected from the old 
genus Nematus. It is closely allied to the genus following it, but differs 
notably in the characters of the head and wings and in the general 
appearance. The males of the smaller species are not so readily sepa- 
rated from the males of Pontania. The genus has its type species in 
Pteronus myosotidis Fab., the only species remaining of those originally 
assigned to it by Jurine. The life-history of a few of t lie American 
species is familiar, as, for instance, that of Pteronus centralis Say (the 
willow sawfly) and 1\ ribe&ii Scop, (the gooseberry sawfly). In habits, 
the other species are for the most pari probably similar to these. Some 
confusion which has grown up with reaped to some of the light-colored 
forms is referred to in the table for the separation of the species. 
TABLE OF SPEC] I 3. 
Females. 
A. Prevailing color black ; pectus always black. 
Stigma narrow, usually straight on lower margin or strongly acuminate, 
elongate, more than three times as Long as wide. 
Bead, thorax, and abdomen black above. 
Stigma and femora brown or black. 
Abdomen beneath black 1. vicinal is Cr. 
Abdomen pale beneath. 
Orbits black 2. oceiden talis n. sp. 
Orbits pale 3. latus n . sp. 
Stigma and femora pale 4. pacificus n. sp. 
Head and thorax black; abdomen more or less pale. 
Abdomen with broad lateral pale stripe 5. I hnbat u s Cr. 
Abdomen with broad, transverse yellow band 6. latifasciatus Cr. 
Stigma broad, rounded on lower margin, not much more than twiee as long as 
wide. 
Head and thorax black ; venter of abdomen pale; dorsal arcs always more 
or less black, except sometimes terminal ones. 
Femora black 7. ventralis Say, 
Hind femora only black 8. marlattii Dyar. 
Femora pale ; orbits black or strongly infuscated. 
Coxa' black; abdomen black above, except narrow apex of some 
of dorsal arcs 9. atriceps n. sp. 
Coxa^ pale; abdomen with narrow transverse brown stripes on 
dorsal arcs, sometimes limited to basal segments, mostly pale; 
sheath pale 10. coloradensis n. sp. 
