Collembola 

 Isotoma viridis var. riparia Nicolet. 



Desoria riparia Nicolet, 1841. — -Gervais, IS 1 1 . 



Isotoma riparia Nicolet, 1847. 



Isotoma palustris var. riparia. Tullberg, 1871. 



Isotoma palustris Tullberg, 1872 (part). 



Isotoma viridis var. aquatilis Schott, 1891. 



Isotoma viridis var. riparia Schott, 1894, 1896, 1902. — Dalla Torre, t895. 

 Reuter, 1895— Schaffer, 1896, 1900a.— Poppe and Schaffer, 1897. -Lie-Petter- 

 sen, 1898.— Scherbakov, 1898a, 1898b.— Carl, 1899.— Wahlgren, lN99a. 1906a, 

 1906b.— Absolon, 1900.— Bonier, 1901a.— Voigts, 1902.— Agren, L903, L904. 

 Axelson, 1903, 1905a, 1906.— (Axelson) Linnaniemi, 1907, 1909, 1911, 1912. 



Ground colour 3^ellowish, greenish or brownish. The principal charac- 

 teristic of this variety is a dark blue or blackish median dorsal stripe. Dark 

 spots on the sides of the body segments may or may not be present. Maximum 

 length, 5 mm. 



The specimens of I. viridis riparia collected by the Expedition arc yellowish 

 or greenish, pale ventrally, with or without the lateral dark spots and with the 

 median stripe complete, or fading out posteriorly. Length, 2.5 mm. 



This variety prefers humid situations, and is found under damp wood, in 

 moss, on the surface of fresh water, along the shores of ponds or si reams and on 

 the seashore under seaweed, driftwood or stones. 



The variety riparia ranges over north and middle Europe, and lias been 

 recorded from Arctic Siberia. 



In Canada, Mr. Charles Macnamara has taken this variety at Arnprior, 

 Ont., in March and April. 



In the United States, the variety is known to me from New Hampshire, 

 New York, Virginia, and Texas, at present. 



A few specimens under loose stones, Bernard harbour, Northwest Terri- 

 tories, May, 1915. F. Johansen. 



Isotoma palustris (Midler). 

 Plate 6, figs. 53-57. 



Podura palustris Mtiller, 1776.— Gmclin, 1778-93.— Bourlet, L843. 



Isotoma palustris Lubbock, 1873.— Reuter, 1876 (part), 1890, 18!' 1. L895. 

 Reuter, L. and O. M., 1880— Tomosvary, 1882.— Parona, 1885. L895. I >ude- 

 mans, 1888.— Dalla Torre, 1888, 1895.— Uzel, 1890, 1891— Parfitt, L891. 

 Schott, 1891, 1894, 1896, 1902.— Lie-Pettersen, 1896, 1898, 1907.— Mac* olhvray, 

 1896.— Schaffer, 1896, 1898, 1900a, 1900b.— Poppe and Schaffer, L897. 

 Scherbakov, 1898a.— Carl, 1899, 1901.— Carpenter and Evans, 1899.— Absolon. 

 1900.— Borner, 1901a, 1902.— Krausbauer, 1902.— Agren, 1903.— Guthrie, L903. 

 Wahlgren, 1906b, 1907.— Collinge, 1910.— Collinge and Shoebotham, 1910. 

 Shoebotham, 1914. 



Isotoma tricolor Packard, 1873 (part).— MacGillivray, 1S«H (pari L896. 



Isotoma aquatilis Lubbock, 1873 (part). — Parona. 1883. 



Isotoma Stuxbergii Tullberg, 1876 (part). 



Isotoma Tullbergi Monicz, 1889. 



Isotoma Stuxbergi Moniez, 1891. 



Isotoma aequalis MacGillivray, 1896. 



Isotomurus palustris Borner, 1903, 1906— Axelson. L905a, L906. I Axelson I 

 Linnaniemi, 1911, 1912.— Imms, 1912. 



Very variable in colouration. The typical form is yellowish or greenish 

 with blue, purple or blackish pigment; having a median dorsal stripe with 

 irregular margins; and frequently lateral spots, which may coalesce to form a 

 stripe on each side of the body. Head often with a dorsal lunate or anchor- 



