THE WATER-MITES (HYDRACARINA) 867 



38 (37) Genital area with numerous acetabula on each side. 



Albia Thon 1899. 



A mite of medium size, averaging 

 about I mm. in length, with elliptical, 

 strongly compressed body; swimming- 

 hairs present. One North American 

 species, rather rare, in lakes of northern 

 states, frequently pale greenish in color. 

 This is identical with the only Euro- 

 pean species, A. stationis Thon, or 

 very closely related. 



Fro. 1339, Albia stationis Thon. Ven- 

 tral surface, female. X 31. Outer side, 

 palpus, female. (After Then.) 



39 (24) Body highly arched, in some cases laterally compressed, with no such 

 dorsal and ventral plate. Subfamily Lebertiinae. . 40 



Legs with swimming-hairs except in certain species of Lebertia. 



i^d (41) Leg IV with claws at tip, epimera only partly fused. 



Lebertia Neuman 1880. 



Medium-sized mites, varying in length from 

 0.8 to 1. 5 mm., with ovoidal body, the surface 

 of which is soft or hard, in some cases with 

 small flecks of chitin, usually striate, but rarely 

 papillate; capitulum developed more or less into 

 a short snout. A genus of frequent occurrence 

 in colder waters, represented by several closely 

 allied species which have only been recently 

 recognized as distinct. 



Fig. 1340. Lebertia tau-insignita (Lebert) , of various 

 authors, Z. dubia Then. This species was referred to 

 North America by Koenike in 1895, but he has re- 

 cently identified three species in the material he 

 studied, all of them hitherto undescribed. Ventral 

 siuface of female. X 19. Outer side, palpus, 

 female. X 70. (Modified from Piersig.) 



41 (40) Leg IV without claws at the tip, ending in a sharp point, epimera 

 completely fused. . 42 



