ARACHNIDES— ACAEINA. 47 



for we have only one species (referred to Limnochares) described by Hey- 

 den from Rott; another from the same locaHty l)ased upon leaf-galls and 

 called Phytoptus antiquus, and a third indicated merely (Aearus) by Heei-, 

 as found at Oeningen. (November, 1881.) 



Gourret has latterly described among the arachnids of Tertiaiy Aix a 

 couple of genera of Acarina with one species each which he regards as 

 belonging to the Trombidid*. (October, 1889.) 



IXODES Latreille. 



No fossil species have before been refei'red to this genus or anywhere 

 near it. The nearest is Aearus, which is only distantly related, belonging 

 indeed to a distinct subfamily. The species of Ixodes, like other ticks, bury 

 themselves in the flesh of animals to suck their blood. (November, 1881.) 



Ixodes tertiarius. 

 PI. 6, Fig. 12. 

 Ixodes tertiarius Scudder, Zittel, Handb. d. Palieont., I, ii, 733, Fig. 906 (1885). 



Although there are few definite salient points in the structure of the 

 single specimen known, its general appearance and its size make it tolerably 

 evident that it belongs to the Ixodidae or Ricini and probably to Ixodes 

 proper. The body is of a very regular ol)ovate form, twice as long as 

 broad, with a slight indication of a frontal shield of a triangular shape (not 

 represented in the plate and perhaps illusory), formed by two sulcations 

 meeting at right angles and terminating just within the front pair of legs on 

 either side. The ro.sti-um is not preserved, but the right palpus (])Oorly 

 given on the plate) is slender and 0.2""" long, or rather projects beyond the 

 body to that amount. Nearly all the legs are present, but the hinder legs 

 of the left side have been crowded out of place and appear on the right 

 side below those which properly belong there, and which apparently are 

 the upper four there seen. The legs are apparently complete, except the 

 terminal appendages, as they all taper rather rapidly at the end, after the 

 manner of ticks; they are stout, short, and of similar length, extending 

 beyond the body by about the width of the latter. 



Length of body, 3.5"""; breadth of same, 1.75""". 



Fish-Cut, Green River, Wyoming. Dr. A. S. Packard, No. 258. 



