NORTH AMERICAN SPECIES OF THE GENUS ATAX 239 



When tilled with ripe eggs the female resembles a large swollen sac, with 

 a cluster of short legs at one, and the more pointed end, which when the 

 mite is in a dish, are quite incapable of serving for support or locomotion 

 and the animal lies helplessly on its back, unable to stir until some object 

 which it can grasp is brought within reach, when its attempts to right 

 itself and to escape from its uncomfortable situation are extremely 

 laboi - ious and in cases of great distension of the body, even utterly vain. 



It possesses a different style of coloring from all other species except 

 in the case of some specimens of A. tumidus, there being no Y-shaped 

 lighter mark upon the back, but the whole body being of a honey-yellow 

 color, deepening to a yellowish-brown on the back, with numerous and 

 irregularly distributed fine white vermiculate lines. 



The eyes are reddish-brown, small and rather widely separated. The 

 maxillary shield is short and broad, and quite evenly rounded posteriorly, 

 though on either side of the median line at the posterior extremity there 

 is a small bulging of the outline due to a thickening of the margin of the 

 shield. On each postero-lateral margin a little behind the middle is a 

 curved chitinous process which runs laterally beneath the first epimeron. 



The mandible is long and slender with an extreme breadth of a little 

 over one-fifth the total length. It is thin and delicate, especially at the 

 ventro-posterior angle where it is produced backward to a distance equal 

 to one third the total length, forming a rectangular plate which is hol- 

 lowed, producing a shallow mandibular furrow. The diameter of the 

 basal joint is greatest just anterior to the posterior dorsal angle and 

 grows gradually less till at the junction of the distal joint it is only about 

 half as great. The distal joint is relatively small, with a claw which is 

 broad, curved, indistinctly angled near the base, and sharply pointed. At 

 the dorsal side of this claw is a thin flattened tapering chitinous process. 



The palpi are moderately heavy and relatively short, averaging only 

 about one-third the length of the body. The first segment is unusually 

 long and much broader at its basal than at its distal end, which is not 

 true of 2, the distal margin of which is twice the breadth of the basal. 

 The ventral margin of 2 is straight, the dorsal moderately convex; on the 

 inner side are four spines, one near the middle at the dorsal sicle,a second 

 a short distance ventrad and posteriad of this, and two others distad of 

 the second, forming with it a row running to the middle of the distal 

 margin. On the outer side of this segment a little proximad of the middle 

 and toward the dorsal side are five small spines, enclosing an area which 

 is a nearly regular pentagon. 3 is stout, its ventral margin nearly 

 straight and more than half the slightly convex dorsal margin, and with 

 a small spine on the inner side near the proximal margin. 4 is rather 

 clumsy, nearly as thick at the distal as at the basal end, and bears two 

 very inconspicuous papillae near the distal margin, and a small spur at 

 the margin, on the ventral side. There is also a short, thick, blade-like 

 spine on the inner side at the distal margin, and 5 has the usual three 

 claws at the blunt tip. The palpi thus possess the general characters of 

 those of other species of Atax, being peculiar in the number of spines on 

 2 and the one on the inner surface of 4. 



