514 TERTIARY INSECTS OF NORTH AMERICA. 



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

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

 the base of the elytra, Length of elytron, 4.5 mm ; breadth, 1.4 mm . 

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



BEROSUS TENUIS. 



PI. 8, Fig. 8. 

 Berosus tennis 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 unusally 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 with it, 

 but is slenderer, and the tip of the elytra is simple ; the punctured stria? 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 shallowly concave front, and apparently smooth surface. 

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

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

 vate, broadest in the middle. 



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



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



TROPISTERNUS Solier. 

 TROPISTERNUS SCULPTILIS. 



Tropisternii* xrutptilis Scudd., Bull. U. S. Geol. Geogr. Snrv. Terr., IV, 7fiO (1878). 



In a specimen and its reverse, of which 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 stria?, more 

 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 delicacv and distance apart : 

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

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



