SMULYAN: NEW ENGLAND TENTHREDELLA. 389 
into a rather broad plateau (the area on each side of it, especially 
on the front, slopes toward it). This plateau is divided by 
sutures or furrows into a number of distinct areas, and the an- 
terior portion is excavated or hollowed out. The plateau begins 
its upward and backward course as two narrow longitudinal and 
usually blunt ridges. These supra-antennal ridges have their 
origin at the bases of the antennae, and each one really begins as a 
dilatation or an upraising of the inner and upper margin of the 
antennal socket. They are invariably more prominent anteriorly, 
at the base of the antennae, and vary somewhat in the degree of 
prominence, as I have tried to indicate by such terms as moderately 
prominent, fairly prominent, quite prominent and prominent. They 
vary also in their backward extent; thus while they generallj^ 
extend, though less prominently, back to the anterior ocellus, 
they may extend to only about half-way there [as in grandis 
(Norton), etc.]; or they may exist only as upraised margins of the 
antennal sockets [as in cogitans (Provancher) ]. The supra- 
antennal ridges form the lateral and longitudinal boundaries or 
walls of the anterior excavation alluded to above and which will 
be referred to as the frontal fovea. The supra-antennal ridge is an 
important generic character, at least as the genus is at present 
defined. The depth of the frontal fovea is directly correlated 
with the degree of prominence of the supra-antennal ridges; 
thus prominent supra-antennal ridges imply a deep frontal fovea; 
fairly prominent supra-antennal ridges, a fairly deep frontal 
fovea, etc. For this reason only exceptional conditions worthy 
of mention will be noted, or when it is desired to emphasize a 
condition. It is often divided in the middle, or slightly above, 
by a transverse swelling — ^the equivalent, probably, of the "frontal 
crest" of authors in other groups. 
Lying above (postero-latcrally) the frontal fovea and anterior 
ocellus are two narrow, elongate plates. They arc broad poste- 
riorly and taper to a point anteriorly and are separated from 
each other mesially, beyond the anterior ocellus, by the stem of the 
A-shaped epicranial suture. Each of these ocellar plates bears 
on its upper portion one of the two posterior ocelli. The epi- 
cranial suture is as a rule well defined, but varies in length, the 
oblique portions or arms being even sometimes practical!}' obso- 
lete [rufopecta rufopecta (Norton)]. 
