442 ANNUAL REPORT OF NEW-YORK 



HICJ5:0RT. BARK. 

 AFFECTING THE BARK. 



159. Four-bristled mite, Oribata quadripilis, new species. (Aptera. 



Acaridae.) 



Under the loose scales of the bark, a broad oval mite of a 

 shining resin-brown color and slightly transparent, with four 

 small bristles projecting forward in front. Length 0.02. 



Though our knowledge of the habits of this mite is very limited 

 and we are not able to say whether it is an injurious species, it 

 still merits a short notice in connection with the other insects 

 which occur upon the bark of the hickory. The Hickory ant 

 which has been mentioned above, in addition to occupying cavi- 

 ties in the interior of the tree is met with also under the loose 

 scales of the bark, in which situation numbers of them may be 

 found crowded together and torpid, in the winter season And 

 associated with it a small mite will frequently be found, which 

 appears to be closely related to the Oribata bipilisj described by 

 Hermann from specimens discovered upon the bark of a tree in 

 Germany. This mite is oval and about half as broad as long, 

 somewhat depressed, polished and shining, of a resin-brown color 

 and slightly transparent like resin. It has in front four project- 

 ing bristles of nearly equal length, the lower two curving inward, 

 the other two straight, and a few bristles occur scattered over the 

 body. The legs are also clothed with hairs of unequal length, 

 and at the tip of each shank is a long bristle extending outward 

 over and projecting beyond the feet. The four anterior thighs also 

 have a shorter bristle at their tips, projecting outward parallel 

 with those of the shanks. The four anterior legs are of equal 

 length and somewhat longer than the hind ones, and the articula- 

 ting part of their base is very narrow and slender. Their thighs 

 are of an elongated ovate form, being strongly inflated into a 

 kind of knot at their bases. In the winter season little groups 

 of these mites are found clustered together in the crevices of the 

 bark, torpid, but reviving when brought into a warm room and 

 thereupon crawling about, though very slowly and awkwardly, 

 the long bristles protruding out beyond the ends of its feet evi- 

 dently serving to aid it in clinging to the surface over which it 

 walks but at the same time impeding it from any briskness in its 

 movements. 



