514 TERTIARY INSECTS OF NORTH AMERICA. 



short supplementaiy stria originates near the base of the second stria, push- 

 ino- it a Httle to one side, and runs into the first stria a short distance from 

 the base of the elytra. Length of elytron, 4.5"'" ; breadth, 1.4°". 

 Green River, Wyoming. One specimen, No. 4079. 



Berosus tenuis. 



PI. 8, Fig. 8. 



Berosus tenuis Scudd., Bull. U. S. Geol. Geogr. Surv. Terr., IV, 760 (1878). 



The single specimen representing this species is preserved on a dorsal 

 view, and is nnusally slender for a Berosus, but seems to fall here rather 

 than in any other of the hydrophilid genera. It is of about the size of B. 

 cuspidatus Chevr. from Mexico, and agrees generally in appearance witli it, 

 but is slenderer, and the Up of the elytra is simple ; the punctured striae are 

 exactly as in that species, as far as they can be made out. The head is 

 large and well rounded, with large round eyes. The pronotum, the poste- 

 rior edge of which is partly concealed by the overlapping base of the elytra, 

 pushed a little out of place, is shorter than in B. cuspidatus, with rounded 

 sides, broadly and shallovvly concave front, and apparently smooth surface. 

 The elytra are long and slender, with entire, bluntly pointed tips, and 

 very delicate, finely impunctured strise. The whole body is regularly obo- 

 vate, broadest in the middle. 



Length of body, 5.65""; of elytra, 4.15""; breadth of body, 2.75"". 



Green River, Wyoming. One specimen, No. 4002. 



TROPLSTERNUS Solier. 

 Tropisternus sculptilis. 



Tropisternus sculptilis Scudd., Bull. U. S. Geol. Geogr. Snrv. Terr., IV, 760 (1878). 



In a specimen and its reverse, of wliich only the abdomen and elytra 

 are preserved, we have a well marked species of Tropisternus of about the 

 size and shape of T. mexicanus Castln., but with rather frequent strife, mo-re 

 distinct than in that species, and composed, not, as there, of rows of 

 impressed points, but of continuous, faintly impressed lines ; the lines are 

 apparently eight in number and uniform in delicacy and distance apart ; 

 the base of the elytra, however, is poorly preserved ; tlie elytra are rather 

 slenderer than in the recent species mentioned, and the extreme tip is 



