CoUemhola 5 a 
Achorutes sensilis, n. sp. 
Plate 2, figs. 12-18. 
Uniform dark blue. Eyes 8 + 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 setae (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 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 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 (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 setae — a 
Avide 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 hai-l^our,, 
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.— MacGillivrav, 1891.— Schott, 
1891, 1894, 1896, 1902.— Moniez, 1894.— Dalla Torre, 1895'— Renter, 1895.— 
Meinert, 1896.— Schafi'er, 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. 
AcJwrutes holetivorus Packard, 1873.— MacGillivray, 1891.— Dalla Torre, 
1895.— Guthrie, 1903. 
-Achorutus marmoratus Packard, 1873. — MacGillivray, 1891. — Harvev, 1893. 
Achorutes texensis Packard, 1873.— MacGillivrav, 1891.— Dalla Torre. 1895. 
Achorutes pratoriwi Packard, 1873.— MacGilfivray, 1891.— Dalla Torre, 
1895. 
