1974] 
Cooper — Boreus 
107 
other aspects of larval and adult anatomy, the complex setation of 
the larval head appears to have been remarkably stable. 
The mandibles of B. notoperates (fig. 4B) are massive, triangular, 
strongly sclerotized, and thrown apically into three, poorly demar- 
cated, blunt teeth. Maxillae and labium are membranous. The max- 
illary cardo is triangular, the stipes large and trapezoidal, the palpi- 
fer (which seems a basal palpal joint) cylindrical and surmounted by 
the subequally 2-jointed maxillary palps, the terminal joint of which 
is cylindrical and densely papillate apically. A brush of closely set 
long hairs is directed medially from each maxillary lobe. The 2- 
jointed labial palps are slender and very elongate. Like the maxillary 
palps, they are testaceous, and bear a cluster of small pegs at their 
tips. The prementum, which is strap-like and sclerotized, bears two 
stout, convergent setae medially at its anterior margin. The sub- 
mentum is large, trapezoidal, and broader posteriorly. 
The numbers and arrangements of setae on the submentum, pre- 
mentum, basal joint of the maxillary palpi, and possibly of the cardo, 
are similar to those figured by Potter (1938a) for B. hyemalis. B. 
notoperates , however, appears to have one less seta on both the palpi- 
fer and stipes, and the conformation of palps, maxillary brushes, 
prementum, and mandibular teeth differ strikingly from that species. 
It also differs from B. hyemalis in shape of head, the presence of a 
complete frontal suture, a distinct epistomal suture, a sclerotized 
clypeal band, emarginate labrum, and details of setal pattern. Brauer’s 
(1855, 1863) descriptions and figures of B. westwoodi do not permit 
a comparison with B. notoperates, but I agree with Potter (1938a) 
that there is no spinneret on the labium as Brauer considered possible 
and as Withycombe (1922) claimed. If Brauer is correct that the 
labial palps of B. westwoodi are 3 -jointed, that is a very striking dif- 
ference from B. hyemalis and B. notoperates. Peterson’s (195 1 ) 
brief description and figures are sufficient to show that the larva of 
B. brumalis has notable differences from both B. hyemalis and B. 
notoperates in head shape, labrum, sutures (only an epistomal suture 
is figured), and setal distribution and lengths on both head and body. 
It is important to emphasize that presence of a distinct epistomal 
suture in the larvae of B. notoperates, B. brumalis, and B. westwoodi, 
because its supposed absence in Boreus is one of the characteristics 
emphasized by Hinton (1958) as a feature of Crampton’s (1930) 
suborder Neomecoptera, only diffidently suggested by Crampton, 
which Hinton elevated to ordinal status. Nor is it the case, as Hin- 
ton supposes, that the eleventh abdominal segment of adult female 
