42 c Canadian Arctic Expedition, 1913-18 
This species resembles -pleurale Malloch in having the mesopleura hairy 
on the supper portion. The third branch of radius in pleurale is very distinctly 
furcate, which is not the case in horealis. 
A female which is in rather poor condition appears to belong to this species. 
In colour it is identical with the male, but it is not possible from the condition 
of the specimen to say whether the mesopleural hairs are present or not. The 
claws are bifid, as in pleurale, but the third branch of radius is as in the male 
of horealis. The basal joint of the hind tarsus is of equal thickness throughout 
its length, its apex is not produced on posterior side, and its length equals 2-5 
the length of second. 
Locality: Bernard harbour, Northwest Territories, August 25, 1916 (F. 
Johansen) . 
Simulium Latreille. 
There are imagines of two species of this genus in the collection. It is not 
possible to definitely associate the larval and pupal material in the collection 
with the adults as no specimens were reared. It is highly probable that the 
pupae I describe in the following pages belong to species represented in the adult 
forms, but there appear to be three distinct species in the former and only two 
in the latter. Unless the species which has sixteen-branched respiratory organs 
is that of Prosimulium horealis, which 4oes not appear probable from what I 
know of the pupse of that genus, there must be a third species that occurs at 
Bernard harbour. 
Simulium, sp. 1. 
This species closely resembles venustum Say in colour, but is larger than the 
average for that species, being nearly 3 mm. in length. The specimen is in such 
poor condition that it is impossible to tell whether the scutum is marked or not. 
The abdomen has the characteristic colouring of the venustum group, the basal 
four segments being opaque black and the apical five shining black dorsally. 
The legs are black, with the fore coxse, trochanters, bases of all femora (narrowly), 
basal half of all tibiae, basal two-thirds of hind metatarsus, and basal half of 
second joint of hind tarsus pale yellow. Mid tarsi missing. Wings clear. 
Halteres yellow. 
It is impossible to say anything about the structure of the tarsal claws as 
the only pair that are left are stuck fast in the mounting medium, and are not 
visible to the extent of showing if they are simple or not. 
Locality: Hood river, Arctic sound, Northwest Territories, August 28, 1915 
(R. M. Anderson). 
Simulium similis, n. sp. 
Female. — Similar to arcticum Malloch in general coloration and in structure 
of tarsal claws. 
Black, subopaque, covered with whitish pruinescence. Antennae, palpi, 
and proboscis entirely black; front and face with dense whitish pruinescence, 
the former very faintly shining; hairs of face and frons whitish yellow, those on 
vertex and upper part of occiput partly brown. Dorsum of thorax, when seen' 
from the front, with an indistinct, broad, whitish pruinose vitta on each side of 
median line, when viewed from behind with the vittae less distinctly whitish 
than the area behind each anterior lateral angle; pile of dorsum all hair-like, 
rather short and depressed; no erect dark hairs distinguishable. A]:)domen with 
basal four segments opaque; the apical five segments very faintly shining; 
surface hairs all yellowish. Legs black, basal two-thirds of fore tibiae dorsally, 
basal third of mid and hind tibiae, basal third or basal joint of mid tarsi, basal 
two-thirds of basal and basal third of second joint of hind tarsi yellowish. The 
tarsal claws are similar to those of arcticum Malloch, but besides the differences 
