HYDROPHILID.E. 43 



HYDROBIUS Leach. 



A cosmopolitan genus with numerous species, of which nearly half 

 come from North America. A couple of existing species have been found 

 in the Pleistocene of Bavaria and Galicia; and in the older Tertiaries ten 

 extinct species occur at Oeningen, Radoboj, Aix, Spitzbergen, Florissant, 

 and in Wyoming. 



Hydrobius decineratus. 



Hydrohius decineratus Scudd. . Bull. U. S. Geol. Geogr. Surv. Terr.. IV, 761 (1878); 

 Tert. Ins. K A., 511, pi. 8, fig. 27 (1890). 



Grreen River, Wyoming. 



Hydrobius confixus. 

 Rydrohim confixus Scudd., Tert. Ins. N. A., 511-512, pi. 7. tig. 25 (1890). 

 Grreen River, Wyoming. 



Hydrobius maceratus sp. nov. 

 PI. V, fig. 3. 



The specimen which is referred here seems to be more nearly related 

 to the smaller forms of Hydrobius than to anything else, though it evidently 

 belongs to a distinct genus on account of the extreme breadth of the pro- 

 sternum, the front and middle coxge being thereby closely crowded together. 

 The slenderness and cylindrical character of the hinder tarsi show that it 

 belongs in this neighborhood, but the imperfect preservation of the single 

 specimen known leaves much to be desired. The legs are rather slender, 

 though the femora are moderately stout, the tibife are considerably longer 

 than the femora, while the very slender tarsi are much shorter and the 

 hinder pair are 5-jointed, the last two joints being equal and longer than 

 the others. There is no sign of any transverse carina in front of the middle 

 cox£e. The insect is of an elongated oval form, with a tolerably large head 

 and an unusually large prothorax, which is much more than half as long as 

 broad. The under surface, and noticeably the prosternum, is faintly, dis- 

 tantly, and rather coarsely punctulate. 



Length, 3.1 mm.; breadth, 1.3 mm. 



Florissant, Colorado; one s])ecimen, No. 780. 



