CoUembola 13 a 
Isotomurus palustris var. yrasina Axelson, 1905a, 1906. — Wahlgren, 1907. — 
(Axelson) Linnaniemi, 1907/1911, 1912. 
Yellowish green or pale yellowish, varying sometimes into yellowish red or 
brownish; imicolorous, or with a trace of the median dorsal stripe. Length as 
great as 4.5 mm. 
The specimens collected by the Expedition are uniform olive green in 
colour, with paler furcula. In some specimens the median dorsal stripe is 
represented, varying from a mere trace to a well-developed line, on head and 
body. In some instances the posterior borders of the body segments are edged 
narrowly with blackish. Maximum length, 3 mm. 
These specimens, which I feel obliged to refer to the species palustris, differ 
from typical European and North American examples of the species in having 
more slender imgues, relatively shorter mucrones, unidentate unguiculi, and 
particularly in lacking the characteristic long fringed sensory setse. Further- 
more, some of the largest of the curving body-setae are feebly denticulate. In 
other respects the specimens agree with palustris, as is evident from mv figs. 
53-57. 
The variety prasina has been recorded from northern and middle Europe, 
Bismarck archipelago, Siberia, Nova Zembla, and Ellesmere land. 
Manv specimens: on ponds at Bernard harbour, Northwest Territories, 
May 25, "l916, June 16, 18, 25, July 9, 1915; under driftwood, Demarcation 
point, Alaska, May 16, 1914. F. Johansen. 
Entomobrya comparata, n. sp. 
Plate 7, figs. 58-63. 
This form, like most other species of its genus, varies greatly in colouration. 
Though the colour varieties intergrade, I have placed them in the following 
three groups for the purposes of description: — 
(1) Pale lemon yellow, including antennae and legs; furcula white. Eye- 
spots black; also basal antennal ring and a transverse band connecting the eye- 
spots and the bases of the antennae. 
(2) Lemon yellow, with black antennal rings and interccular band, and 
black median subcrescentic spot behind the eyes (fig. 58). Anal segment black 
dorsally. Antennae purphsh distally. Legs and furcula yellow. This is the 
commonest form in the collection. 
(3) General colour brownish yellow, faintly and minutely mottled with 
pigment. Segments bordered narrowly with black, as well as the posterior 
l)order of the fourth abdominal segment, as in fig. 59. Anal and genital seg- 
ments black dorsally. Fourth and fifth abdominal segments with a variable 
amount of pigment ventrally. First antennal segment l)lackish apically; 
remaining segments blackish. Femora and tibio-tarsi pigmented distally, ancl 
the manuljrium dorsally. 
Eyes 8 + 8, unequal (fig. 60). Antennae a little more than twice as long 
as the head, with segments in relative lengths about as 4:10:9:12. Abdominal 
segments in relative lengths as 13:19:14:40:6:4. Fourth abdominal segment 
therefore about three times as long as the third. Unguis (fig. 61) with a pair of 
lateral teeth and with inner margin tridentate in profile; all three teeth being 
actually doubled, however. Unguiculus extending a little beyond the middle of 
the unguis, broadly lanceolate, simple. One clavate tenent hair. Dentes one 
third longer than manubruim. .Mucrones half as long as hind unguiculi, of the 
usual form (fig. 62). Rami of tenaculum quadridentate; corpus with one stout 
cur.ving seta (fig. 63). General clothing of dense short curving fringed setae. 
Dorsum of head and body with dense clavate fringed setae, less abundant on the 
last three abdominal segments. Antennae and legs densely setaceous. A few 
long fringed sensory setae occur as usual. Length, 1 .7 mm. 
