512 TERTIARY INSECTS OF NORTH AMERICA. 



incised striae, which are apparently accompanied (not shown in the plate) 

 by very faint and rather infrequent punctures ; all the strife can be traced 

 almost to the very tip of the elytron, some of them uniting, or almost uniting, 

 as shown in the plate. The outer edge is not very well preserved, and 

 doubtless a tenth stria is concealed there. 



Length, 4 ram ; breadth, 1.7 mm . 



Green River, Wyoming. One specimen, No. 79 (Dr. A. S. Packard). 



PHILHYDRUS Solier. 

 PHILHYDRUS PRIM^VUS. 



PL 8, Fig. 5. 

 Philhydrug primcevua Scudd., Bull. U. S. Geol. Geogr. Surv. Terr., II, 78 (1876). 



A single specimen, wanting head, thorax, and legs, but exhibiting at 

 once the upper and under surface of the body (like specimens mounted after 

 a potash bath), represents this species, which is poorly drawn on the plate, 

 the striae being too far apart and only a portion of them shown. The elytra 

 taper on the apical third, following the narrowing form of the abdomen, and 

 are delicately pointed ; they are furnished each with six straight, equidis- 

 tant rows of distinct, longitudinal, punctate striae, 0.19 mm distant from one 

 another. 



Length of elytra, 3.8 mm ; breadth of same, 1.35 mm . 



Green River, Wyoming. One specimen. No 15199 (F. C. A. Rich- 

 ardson). 



PHILHYDRUS spp. 



Two specimens (Nos. 4033, 4042) of species of Philhydrus were found 

 by Mr. F. C. Bowditch and myself at the same Green River locality, but 

 neither of them is very perfect, representing little else than elytra, and these 

 rather obscurely preserved. The larger species has smooth elytra ; the 

 elytra of the other have eight delicate striae, which apparently are not punc- 

 tured. Possibly one or both should be referred to Hydrobius. 



Length of elytra of larger species (No. 4033), 4 mm ; breadth of body, 

 3 2 mm . 



Length of elytra of smaller species (No. 4042), 3.75 mm ; breadth of 

 body, 3 ram . 



Mention of these was made by me in the Bull. U. S. Geol. Geogr. Surv. 

 Terr., IV, 761 (1878). 



