Collembola 5 a 



Achorutes sensilis, n. sp. 



Plate 2, figs. 12-18. 



Uniform dark blue. Eyes 8 -l^ 8. Postantennal organs (fig. 12) small, 

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

 Antennae shorter than the head, with segments in relative lengths about as 

 5:6:7:7. Third antennal segment with many distal lateral sensory sets (fig. 13). 

 Unguis (fig. 14) long, slender, feebly curving, unidentate 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. Rami 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, 16), with broad outer lamella and narrow inner lamella. 

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

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

 short stout curving setae and longer stout suberect setse, the latter often feebly 

 dentate. Maximum length, 2.2 mm. 



I regarded this form as being A. viaticus TuUberg, until I found the pecuhar 

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

 European specimens, the sense organ of t^e 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 (fig. 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 setse — a 

 wide departure from the condition typical for the genus. The other differences 

 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 somewhat shorter, stouter, and less 

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

 suberect setse 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 3, figs. 21-25. 



Podura armata Nicolet, 1841. 



Achorutes armatus Gervais 1844. — Nicolet, 1847. Lubbock, 1868, 1873. — 

 Tullberg, 1871, 1872, 1876.— Parona, 1879, 1882, 1888, 1895.— Tomosvary, 

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

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

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

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

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

 1901a.— Krausbauer, 1902.— Willem, 1902.— Agren, 1903, 1904.— Axelson, 

 1905a, 1905b, 1906. — (Axelson) Linnaniemi, 1907, 1909.— Colhnge and Shoe- 

 botham, 1910.— Imms, 1912.— Shoebotham, 1914.— Folsom, 1916. 



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

 1895.— Guthrie, 1903. 



Achorutus marmoratus Packard, 1873.— MacGillivray, 1891.— Harvey, 1893. 



Achorutes texensis Packard, 1873.— MacGillivray, 1801.— Dalla Torre, 1895. 



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

 1895. 



