NORTH AMERICAN APTERYGOGENEA. 185 



Isotoma lacustris Schott. 



Dark violet. The eyes are sixteen, eight on each side 

 of the head. The antenna are not longer than the head, 

 and have the three outer joints of nearly the same length. 

 The third abdominal segment is shorter than the fourth. 

 The claws are unarmed. The caudal appendage reaches the 

 ventral tube. The denies are all over of the same breadth. 

 The macro is formed out of thin chitinous lamels, and 

 provided with two hooks. Length 2 mm. 



Syn. 1893, Isotoma litoralis Schott, Zur Syst. u. Verbr. 

 palsearct. Coll., p. 75. 



I have changed the name of the above species because 

 Monier, in his valuable paper, *Acaricus et Insectes 

 marines des cotes du Boulonnais, has already before made 

 use of the specific name littoralis for an Isotoma described 

 by him. 



/. lacustris Schott has a special interest, because of 

 its near relation to I . crassicauda Tullb. Having before 

 in my memoir Zur Syst. und Verbr. pala^arct. Coll., put 

 forth the distinguishing marks of the two species, I will, 

 however, give some detail figures illustrating the fact 

 stated. 



Habitat. The vicinity of Lake Chabot, near Oakland, 

 California. (Coll. G. Eisen.) 



Family LIPURID^ Lubbock. 



Mr. MacGillivray, in his valuable memoir on North 

 American Thysanura, proposes to alter several of the 

 names now commonly used for the genera of the family 

 LipuridcB. I have no objection to abandoning the generic 

 terms Anura Gerv. and Lipura Burm., both being, as 

 the author justly observes, "preoccupied in Mammal- 

 ogy." (Gray gave, in 1838, the name of Anoura to a 



*Extrait de la Revue Biologiquedu Nord dela France. Lille, 1890, p. 32. 



