760 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



hind border gently convex ; the scutellum is large, triangular, a little 

 longer than broad. The surface of the thorax and elytra is apparently 

 smooth ; at least, no markings are discoverable, excepting the line of the 

 inner edge of the inferior margination of the sides of the elytra, which 

 appears through the latter, as do also the abdominal incisures and the hind 

 femora and tibise. These legs are longer and slenderer than in T. hino- 

 tatus, the femora extending beyond the sides of the abdomen, and the 

 tibise are armed beneath at tip with a pair of slender spines, which 

 together with the tibise are about as long as the femora. 



Length of body 6.65""", of elytra 4.45'"""; breadth of middle of body 

 3.25'""'; length of hind femora 2""", of hind tibise 1.25""". 



Tropisternns sciiJptilis. — In a specimen (No. 3989) 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. mexlcanus Oastln., but with 

 rather frequent strisB, 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 delicacy 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 rounded and not acutely pointed. Dis- 

 tinct striation of the elytra is rare in Tropisternus^ but it scarcely seems 

 possible to refer this species elsewhere. 



Length of elytra 6.5"""; breadth of combined elytra 5""". 



Berosus tenuis. — The single specimen (No. 4002) representing this 

 species is i^reserved on a dorsal view, and is unusually slender for a 

 Berosus, but seems to fall here rather than in any other of the Hydro- 

 philid 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 strise 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 posterior 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 irapunctured striss. The whole body is regularly 

 obovate, broadest in the middle. 



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



Berosus sexstriatus. — A single well-preserved elytron (No. 4079) repre- 

 sents a species scarcely smaller than B, punctipennis Ohevri (undescr.) 

 from Mexico, with the elytra of which it also agrees in the character of 

 the tip and in the shape of the whole, unless in the fossil it tapers more 

 toward the base; the latter is also remarkable for the absence of the two 

 lateral strise, the others retaining their normal position; for the delicacy 

 of the strise themselves, which are even more faintly impressed than iu 



