INTRODUCTION. 
—— Se aoe S) 
SS a —— 
It may be well at the outset to indicate the extreme dissimilarity of 
the Tribes now grouped under the collective term Tryphoninae. These 
are not only structurally, but biologically distinct, in that the Metopiides 
and Exochides prey upon Lepidoptera only, the former on large species 
and mainly Bombyces, the latter on small species and mainly Tortrices ; 
the Bassides attack only Diptera, probably exclusively Syrphidae; the 
Tryphonides are confined to the extermination of Sawflies, for I am 
convinced that the few species of lepidopterous parasites still here 
retained in our artificial classification are misplaced. Thus the cocoon 
of Euceros exactly resembles those of the Pimplid Lissonotides, many of 
whose females have but shortly exserted terebra and very similar sculp- 
ture; Scolobates was treated of under the Ophioninae by Holmgren, and 
though relegated to the present subfamily by subsequent authors, there 
are many points of agreement therewith in the genus. The Sphinctides 
are so entirely unique in conformation that I have not considered it 
necessary to place our single species in the table of tribes; the discovery 
of a second representative of the genus from India conducts us no further 
to a knowledge of its natural position, which is apparently closest in the 
structure of both imago and cocoon to Metopius. 
Further evidence of the unnatural association of the tribes is furnished 
by their geographical distribution. The Bassides, Metopius and probably 
Exochus are found generally throughout the globe; while the Tryphonides, 
on the other hand, are very nearly confined to the temperate regions of 
both hemispheres, extending from southern Lapland hardly beyond the 
Mediterranean and eastward to the central altitudes of the Himalayas, 
while they abound in the United States and southern Canada, though 
becoming less frequent in Mexico. I recall having seen none from so 
far south as the twentieth degree of latitude; and this is accounted for 
by the infrequency there of Sawflies, upon which all their genuine species 
exclusively prey, though further research will doubtless prove the existence 
of Tryphonides indigenous to the few Australasian Tenthredinidae. ; 
Gravenhorst placed Trachyderma (Tylocomnus, Holmgr.) under Pimpla, 
in ignorance of its female; Metopius, Euceros and Orthocentrus he 
united to Bassus in his eighth genus; while Tryphon consisted of 
Sphinctus, Scolobates and Exochus with Mesoleptus and Tryphon, under 
