Diptera 43 c 
in colour evident from the above description there are no long erect dark hairs 
on thoracic dorsum as in that species. 
Length, 2-3 mm. 
Type locality: Hood river, Arctic sound, Northwest Territories, August 28, 
1915 (R. M. Anderson). Paratypes, Bathurst inlet, Northwest Territories, 
September 1, 1915 (R. M. Anderson). 
This species is closely related to arcticum Malloch, described from British 
Columbia, but the points mentioned in the description should serve to separate 
the species. 
Simulium, sp. 2. 
Pupa. — This species is similar to johannseni Hart in having the thoracic 
respiratory organs each four-branched (PI. VI, fig. 4). There is also a Euro- 
pean species with this characteristic. From johannseni the present species 
differs in the armature of the abdomen. The third and fourth dorsal segments 
each have eight stout anteriorly directed thorns near the posterior margin, in a 
transverse series, four on each side, the space between each series of four about 
three times as wide as the space between the thorns of each series; dorsal seg- 
ments five to eight inclusive, each with a transverse series of weak, backwardly 
directed spines near anterior margin, the series of fifth segment much shorter 
than that on sixth, those on other segments becoming progressively longer and 
stronger as they near apex; apical segment with two short spines; fourth, fifth, 
and sixth ventral segments each wdth two short spines on each side. 
Length, 3 mm. 
Locahty: Bernard harbour. Dolphin and LTnion strait, Northwest Terri- ■ 
tories, August 16, 1915, in bed of river (F. Johansen). 
Simulium, sp. 3. 
Pupa. — Differs from the foregoing in having the thoracic respiratory organs 
each with twelve or thirteen branches (PI. VI, fig. 13) and the armature of the 
abdomen as follows. Third and fourth dorsal segments each with eight very 
small recurved thorns arranged as in the previous species, fifth segment with 
the anterior transverse armature almost imperceptible, that on sixth, seventh, 
and eighth consisting of a series of very small, closely placed spinules that 
extends entirety across the surface from side to side; apical segment with two 
very conspicuous upwardly curved thorn-like processes, fifth ventral segment 
with a pair of small thorns on each side near posterior margin, sixth and seventh 
each wdth one such thorn similarly located. 
Length, 3-5 mm. 
Locality: Bernard harbour, Dolphin and Union strait, Northwest Terri- 
tories, July 10, 1916 (F. Johansen). 
Simiulium^, sp. 4. 
Pupa.- — Differs from the previous species in having sixteen-branched 
thoracic respiratory organs (PL VI, fig. 12). The abdominal armature is as 
follows: second dorsal segment with eight minute spines on each side — three in 
a submedian transverse group, three in a sublateral similarly disposed group, 
and two midway between these groups; third and fourth segments each with 
the same number of spines as second, but they are stronger, more appreciably 
recurved apically, and the submedian and intermediate series are not so distinctly 
separated and appear as a single rather irregular series of five thorns; fifth and 
sixth segments without well-developed spinules anteriorly; -seventh and eighth 
each with a complete series of spinules near anterior margin; apical segment 
wi^h two to three small spines on each side; third ventral segment with two 
thorns on each side, fourth with three, fifth with two, and sixth with one. 
