38 TERTIARY COLEOPTERA OF NORTH AMERICA. 



species of seventeen genera are now known, of which only six of four 

 genera an- referred To living forms; these last are all from Pleistocene 

 deposits in Europe, which have also yielded seven extinct species of four 

 genera, besides which two species of different genera have been found in 

 America. To the older Tertiaries belong forty-five species of ten genera 

 iu Europe and fourteen species of eight genera in America, the same 

 genera being represented on both continents in three cases if only the older 

 fossils are considered, in five cases if all are taken into account. Three of 

 the European genera from the older formations are regarded as extinct. 



HELOl'IIOHUS Fabric-ins. 



A tolerably prolific genus, mainly north temperate in distribution, with 

 about a dozen North American species. Five extinct species have been 

 found in Pleistocene deposits in Galicia and Ohio, and two in the older 

 Tertiaries of liaden. 



HELOPHORUS RIGESCENS. 



ll,l<>l>li<>,-iix r'njcKcens Scudd., Tert. Ins. N. A., 516-517, pi. 1, %. 53 (1890); Contr. 

 Csuuul. Pahvont.. II. 45 (180:.'). 



Clay beds near Cleveland, < )hio. 



HYDROCHUS Leach. 



A dozen species of this genus exist in North America, being nearly half 

 the known species, the others occurring in the north temperate regions of the 

 Old World. The only fossil species known are the two here recorded, one 

 each from the Pleistocene of Ohio and the Oligocene of Wyoming. 



HYDROCHUS AMICTUS. 



ll>l<lrn<-lnix amictus Scudd., Tert. \\\^. N. A., 515-5 Itl. pi. 1, ML;-. 47 (iS'.Hi); Contr. 

 Caiiad. Pab'ont., II. 45 (lS!f_>). 



Clay beds near ( 'levclaiid, Ohio. 



llviiRorins KKLKTrs. 



/</.v r< Tii-hot Scudd.. Tert. Ins. N. A.. 51tl. pi. ,s. liy. 11 

 ( ireen River, W\-omin^. 



