Collembola i;; A 



Isotomurus palustris var. prasina Axelson, 1905a, 1906. Wahlgren, 1907. 

 (Axelson) Linnaniemi, 1907, 1911, 1912. 



Yellowish green or pale yellowish, varying sometimes into yello\vi>h red or 

 brownish; unicolorous, or with a trace of the median doi>;tl stripe. Length as 

 great as 4.5 mm. 



The specimens collected by the Expedition arc uniform olive green in 

 colour, with paler furcula. In some specimens the median doi>:d -tripe i- 

 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 - 

 narrowly with blackish. Maximum length, 3 mm. 



These specimens, which I feel obliged to refer to the >pe< -ies /Hiluxtri*. differ 

 from typical European and North American examples of the species in having 

 more slender ungues, relatively shorter mucrones, unidentate imgiiiculi. and 

 particularly in lacking the characteristic long fringed sensory setffi. 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 m\ 

 53-57. 



The variety prasina has been recorded from noil hern and middle Kurope. 

 Bismarck archipelago, Siberia, Nova Zembla, and Ellesmere land. 



Many specimens: on ponds at Bernard harbour, Northwest Territories. 

 May 25, 1916, 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 antenna? 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 purplish 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 

 border 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 blackish apioully; 

 remaining segments blackish. Femora and tibio-tarsi pigmented distally, and 

 the manubrium dorsally. 



E ves 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). Kami of tenaculum quadridentate; corpus with one stout 

 curving 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. 



