GOLEOPTEKA— CARABIDJ?: 519 



P. crenistriatus LeC and P. rubripes Zimm., in which the strifE are coarse 

 and punctured, the sutural stria insignificant or obsolescent, and the surface 

 texture a very delicate transverse ribbing nowhere broken up into a 

 reticulation. 



Platynus senex. 



PI. 7, Fig. 38. 



Platynus senei Scudd., Bull. U. S. Geol. Geogr. Surv. Terr., IV, 759, (1878.) 



This species is represented by a single specimen and its reverse. The 

 upper surface is shown with none of the slenderer appendages. The true 

 form of the head can not be determined, as the edges are not preserved. 

 The prothorax is unusually square for a carabid, resembling only certain 

 forms of Bembidium and Platynus, and especially P. variolatus LeC. It 

 is, however, still more quadrate than in that species, and differs from it in 

 shape, being a little broader than long, broadest just behind the middle, 

 tapering but little anteriorly, and scarcely more rapidly at the extreme 

 apex; the elytra are together only about half as broad again at base as 

 the thorax, and are furnished with eight very faint and feeble striae, appar- 

 ently unpunctured, the one next the margin interrupted by four or five 

 foveai on the posterior half of the elytra; the humeral region is too poorly 

 preserved to determine the striae at that point ; the form of the elytra is as 

 in P. variolatus. 



Length of body, G.l""°; breadth of thorax, L5°"" ; of base of elytra 

 together, 2.3""; length of elytra, 4.1"". 



Green River, Wyoming. One specimen, Nos. 3998 and 3992. 



Platynus casus. 



PI. 1, Fig. 42. 



A single elytron is preserved in the beds which have yielded so many 

 Platyni, which seems to be better comparable with P. rubripes Zimtn. than 

 with any other living form, but better still witli the fossil forms from the same 

 beds, with which it agrees also better in size, though it is a trifle broader, 

 with a considerably more rounded humeral angle, a more rounded outer 

 margin, and the first stria closely approximated to the suture. Except in 

 these particulars it agrees best with P. halli ; but, somewhat as in P. rub- 

 ripes though with less regularity in size and distribution, tlie interspaces 



