23*2 DR, JOHNSTON ON THE ACARIDES OF BERWICKSHIRE. 



6. At AX HISTRIONICUS. 



Atax histrionicus, Dugh in Ann. des Sc. Nat. (1834) i. p. 147, 



pi. 10, lig. 13-17. 



Body globose, smooth, of a transparent hyacinth-red colour, 

 with 5 rather undefined dark spots, 2 on the shoulders, two be- 

 hind, and one medial between the scapular ones : posterior 

 part of the abdomen marked with an irregular dusky line 

 forming almost a circle : coxw and genital plates blueish grey, 

 the latter oblong, rounded on the angles, with 6 stigma-like 

 tubercles, 4 behind and 2 anteriorly : Palpi 2, pediform, fur- 

 nished with a few scattered short bristles, porrect, approxi- 

 mate, one- third the length of the body, thicker than the legs 

 but of the same colour, 4-jointed ; basal joint minute, 2d and 

 3d thick and equal, 4th elongate, slender, tapered to a point 

 and terminated with a curved claw : Legs 8, alike, slender, 

 tapered, of a watery blueish-grey colour, hirsute, longer than 

 the body, 6-jointed ; 1st, 2d, and 3d joints nearly equal and 

 shorter than the 4th, which again is shorter than the 5th and 

 6th, the latter terminated with two small claws retractile 

 within an oblong sinus above their insertion ; the tarsal joint 

 of the posterior legs, however, has not the two claws but is 

 sim})ly pointed, and has a long stiff bristle originating in an 

 indentation a little above the end and projecting consider- 

 ably beyond it : of the legs, the hinder pair is the longest, 

 then the 3d, 2d, and 1st are successively shorter ; the bristles 

 of the first pairs are comparatively few and short, and their 

 tarsal and penultimate joints are naked, there being bristles 

 only at the articulations ; but the posterior pairs are more 

 bristly, and the bristles on the outer edge of the fourth and 

 fifth joints are long, the tarsal joint being comparatively 

 naked 



Til is description is made from a specimen taken in the 

 pond at Netherl)yres, Aug. 20, 1847. It is beautifully figured 

 by Dug(^s ; and is a beautiful species, the blueish members 

 contrasting remarkably with the red body. In Dug^s' figure 

 the middle spot in front is represented more forAvard than it 

 was in our specimen ; but as he assures us that these dorsal 

 spots all proceed from the viscera indistinctly visible through 

 the skin, they may be supposed to vary somewhat according to 

 the state of repletion of the insect. On the inferior edge of 

 the second joint of the palpi there is a minute papilla, the 

 use of which is unknown. 



