Collembola 5 A 



Achorutes sensilis, n. sp. 



Plate 2, figs. 12 7 18. 



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



slightly longer than the diameter of an eye, with lour peripheral mix 

 Antennae snorter than the head, with segments in relative lengths about a> 

 5:6:7:7. Third antennal segment with many distal lateral sensorj 

 Unguis (fig. 14) long, slender, feebly curving, unideutate two-fifth- from tin- 

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

 subovate and distal half acuminate. One long knobbed teneut hair. All tin- 

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

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

 long curving subapical dorsal seta. Mucro about as long as hind iinguiciilus. 

 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 in, 

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

 short stout curving setae and longer stout suberect setae, the latter often feelily 

 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 (fig. 13), two pairs of sense 

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

 seated in apit and covered basally with an integumentary fold; and in addition 

 as many as nine lanceolate accessory sensory setae, with five guard setae 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 setae 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 Sohott, 

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

 Meinert, 1896. SchafTer, 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. Collinge 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, 1891. Dalla Torre, 1895. 



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

 1895. 



