Collembola 7 A 



Unguis (fig. 30) slender, curving, unidentate beyond tin- middle of the inner 

 margin. Unguiculus exceeding the unguis, slender, gradually tapering from the 

 base into a fine filament. Anal spines (fig. 31) two, feebly curving, hall u long 

 as hind ungues, on separated papillae, one-fourth as long as the spines. ( 'lothing 

 (fig. 32) of short curving simple setae, with long erect simple sensory 

 Length, 2.4 mm. 



This species belongs near the common armatus Tullberg, and conn- nearest 

 to octopunctatus Tullberg, a rarely recorded species that has never been fully 

 described. If the form here described proves to agree with octopunclut 

 respect to pseudocelli and the minute structure of the antennal sense organ-, it 

 should be regarded as a variety of that species. 



Three cotypes, from rotten driftwood at Bernard harbour. Northwest 

 Territories, June 19, 1915. F. Johansen. 



Tetracanthella wahlgreni Axelson. 

 Plate 4, figs. 33-37; plate 5, figs. 38-41. 



Tetracanthella pilosa Schott, 1894 (part), 1902 (part). Lie-Pet tersen, 1896. 

 Wahlgren, 1899b, 1900b, 1906b. Axelson, 1900. 



Tetracanthella coerulea Schaffer, 1900a, 1900b. 



Tetracanthella wahlgreni (Axelson) Linnaniemi, 1907, 1912. Bagnall, 1914. 



Dark blue. Body elongate, narrowing posteriorly (fig. 33). Eyes on 

 black patches, 8 + 8 (fig. 34) ; the two inner proximal eyes of each side smaller 

 than the others; the three posterior eyes in a group apart from the five anterior. 

 Postantennal organs (fig. 34) elongate, subelliptical, eight or nine times as long 

 as broad, and four times as long as the diameter of an adjacent eye; sometimes 

 constricted near the middle. Antennae shorter than the head, with segment s in 

 relative lengths about as 9:13:10:19. Sense organ of third antennal segment 

 (fig. 35) consisting of a pair of slender curving sense rods, subtended by a thick 

 chitinousridge, and covered with an integumental fold. Fourth antennal segment 

 with subapical papilla and with slender curving sensory setae. Second, third. 

 and fourth abdominal segments subequal in length dorsally. Genital and anal 

 segments confluent, bearing two pairs of spines (figs. 36, 37). Posterior spines 

 a little longer than hind ungues, feebly curving, on stout papillae almost half as 

 long as the spines. Anterior spines similar to the posterior, but a little shorter. 

 Ano-genital segment with long stiff hairs projecting beyond the apex of the 

 abdomen, which are simple in some specimens but apically bent and knobbed 

 in others. Anus ventral. Unguis stout, untoothed (fig. 38). Unguiculus 

 extending half to three-fifths as far as the unguis, lanceolate, acuminate. Clavate 

 tenent hairs two, extending as far as, or farther than, the unguis. Femur with 

 a single long clavate hair (fig. 33). Furcula short, appended to the fourth 

 abdominal segment, and extending to the posterior margin of the third. Manu- 

 brium stout, with several pairs of dorsal setae (fig. 39). Mucro and dens not 

 demarkated from each other. Mucro-dentes convergent, in form as in figs. 39 

 and 40; each with three setae: two dorsal and one ventral. Kami of tenaculum 

 bidentate (fig. 39); corpus with a single stout seta. General clothing of few 

 short equal curving simple setae in the middle region of each segment, with long 

 outstanding simple sensory setae in a single transverse series on most of the body 

 segments (fig. 41). Cuticula not tuberculate, but figured. Length, 1.8 mm. 



The term figured, as applied to the cuticula, means that the integument is 

 divided into minute polygonal areas. 



In two specimens the long distal hairs of the abdomen were simple ; in one 

 specimen, however, they were distinctly bent apically, with a minute terminal 

 knob, as in my fig. 36. Linnaniemi ('12, p. 104), not having seen these clavate 

 hairs as described by Schott, suggested that the appearance of terminal knobs 

 was due to adherent particles of foreign matter. 



