NORTH AMERICAN SPECIES OF THE GENUS ATAX 221 



cosus, from Black Lake, Holland, Mich. , while the past summer 

 it was found in TJ. luteolus from White Lake, Muskegon County, 

 Mich. 



At Oshkosh, Wis. , the species was found during September, 

 1897, in TJ. gracilis and TJ. luteolus from Lake Winnebago. 

 In Illinois, as determined from specimens received from Prof. 

 H. M. Kelly and Mr. M. Ricker, A. abnormipes has been taken 

 from TJ. anodontoides, TJ. gracilis and TJ. occidens collected at 

 Havana. Finally in material received from Mr. R. H. Johnson 

 and obtained at Chautauqua Lake, N. Y., it occurred in TJ. 

 luteolus and TJ. phaseolus and perhaps in Anodonta plana, 

 though the record is doubtful, while it also was present in 

 mites taken from TJ. ventricosus at Cheektowaga, Erie County, 

 X. Y. 



6. A. INDISTINCTUS WOLCOTT. 



Atax indistinctus Wolcott, 98; 281. 



The second species of Atax referred to under the head of the preced- 

 ing is A. indistinctus, which received the name it bears when only 

 females had been collected, and in reference to the close resemblance be- 

 tween the females of the two species, which were only separated by the 

 most careful observation. Since the preliminary paper in which this was 

 described has been published an abundance of males have been secured 

 and the species shown to be entirely distinct though closely allied. 



A. indistinctus is a species rather under medium size and yet a little 

 larger than A. abnormipes, the measurement of several males showing a 

 variation in body length of from 0.675 mm. long by 0.55 mm. broad to 0.75 

 mm. long by 0.618 mm. broad, while the average of a number of females 

 was 0.825 mm. by 0.63 mm. It is similar in form to A. abnormipes, and 

 like that species the whole surface of the body is marked off by fine lines 

 into small hexagonal areas. 



Eyes large but not quite so large as in the preceding species, and 

 about the same distance apart. 



Maxillary shield similar to that of A. abnormipes, but the posterior 

 lateral angles not so prominent and the sides in front of it slightly diverg- 

 ing instead of parallel. Rostrum rather prominent. 



Mandibles similar to those of A. abnormipes in form. 



Palpi rather slender but not so much so as in those of the previous 

 species. The spines are similar in number and position to that form, the 

 two on the outer side of 2 dividing it into thirds. The distal margin of 

 this segment is not uniformly concave but a shallow re-entrant angle 

 separates the extensor two-fifths and the flexor three-fifths of its length. 

 A rounded angle in the proximal margin of 8 corresponds to this, the 

 segment being proportionately heavier than in the allied species, while 4 is 



