Collembolq 



Achorutes sensilis, n. sp. 

 Plate 2, figs. 12 L8 



Uniform dark blue. Eyes 8 + 8. Postantennal organs (fig, 12 small, 

 slightly longer than the diameter of an eye with four peripheral tubercles. 



Antenna' shorter than the head, with segments in relative lengths aboul 

 5:0:7:7. Third antennal segment with many distal lateral sensory s< tae fiu. 13 . 

 Unguis (fig. 14) long, slender, feebly curving, nnideniate two-fifths from the 

 apex. Unguiculus extending one-half as far as the unguis, with proximal half 

 subovate and distal half acuminate. One long knobbed tenent hair. All the 

 distal tibio-tarsal setae are apically bent and minutely knobbed. Kami of 

 tenaculum tridentate. Dentes three times as long as mucrones, each with a 

 long curving subapical dorsal seta. Mucro about as long as hind unguiculus, 

 variable in form (figs. 15, lb), with broad outer lamella and narrow inner lamella. 

 Anal spines (fig. 17) short, stout, feebly curving, one-fifth as long as hind ungut s, 

 on contiguous papillae one-third as long as the spines. Clothing (fig. 18 of few 

 short stout curving seta- and longer stout suberect seta\ the latter often feebly 

 dentate. Maximum length, 2.2 mm. 



I regarded this form as being A. viaticus Tullberg, until I found the peculiar 

 sense organs of the third antennal segment. In viaticus, of which I have many 

 European specimens, the sense organ of the third antennal segment is as in 

 figure 19, with a pair of sense rods, a single finger-like accessory seta, and one 

 guard seta. In this new species there are, however (fiii. 13), two pairs of sense 

 rods, each pair with the usual basal ridge; also a distal ovate petiolate papilla, 

 seated in a pit and covered basally with an integumentary fold: and in addition 

 as many as nine lanceolate accessory sensory setae, with five guard seta' — a 

 wide departure from the condition typical for the genus. The other different - 

 between the two species are of minor importance. In sensilis, as compared 

 with viaticus, there are not three long knobbed tenent hairs; the tenaculum is 

 not quadridentate; and the anal spines are somewhal shorter, stouter, and l< ss 

 curving. The clothing is of the same general type in the two species; the -tout 

 suberect seta? of the body being, however, somewhat shorter than in viaticus 

 (compare fig. 18 with fig. 20). 



This species occurred in masses on the surface of a pond at Bernard harbour, 

 Northwest Territories, July 5, 1916. F. Johansen. 



Achorutes armatus (Nicolet). 



Plate ::. figs. 21 25. 



Pod unt armata Nicolet. 1841. 



A chorutes armatus Gervais 1844. Nicolet. 1847. Lubbock, 1868, 1873 

 Tullberg, 1871, 1872, 1876— Parona, 1879. 1SS2. 1SSS, IS95. Tomosvary, 

 1883.— Oudemans, 1890.— Uzel, 1890, 1891. MacGillivray, 1891. Schott, 

 1891, 1894, 1896, 1902.— Moniez, 1894.— Dalla Torre, 1895. Reuter, 1895.— 

 Meinert, 1896— Schaffer, L896, 1897, 1900a, 1900b. Carpenter. IMC. Lie- 

 Pettersen, 1896, 1898.— Poppe and Schaffer, 1897. Scherbakov, 1898b, 1899a.— 

 Carl, 1899, 1901— Carpenter and Evans, 1899. Wahlgren, 1900a. Borner, 

 1901a.— Krausbauer, 1902. W'ilbin. 1902. Agren, 1903, 1904. /keelson, 

 1905a, 1905b, 1906. — (Axelson) Linnaniemi, 1907. 1909. Collinge and Sh< 

 botham, 1910. Iimtis, 1912. Shoebotham, 1914. Folsom, 1916. 



Achorutes boletivorus Packard, 1873. MacGillivray, 1891. Dalla Torre. 

 1895.— Guthrie, 1903. 



A chorutus marmoratus Packard, 1873. MacGillivray, 1891. Harvey, l v 

 Achorutes texensis Packard, 1873. MacGillivray, 1891. Dalla Torre, 1895 

 Achorutes pratorum Packard. 1873. MacGillivray, 1891. Dalla Torre. 

 1895. 



