8 TERTIAIJY RIIYNCirOPriOROUS COLEOPTERA. 



Relative abundance of the orders of Insects in different western deposits. 



Orders. 



Hympiioptera 



Dipt-cni 



Culi'f)))t('rai 



Hciiiiiitcni - .. 

 Orthoptera . . . 



Neuroi)t('ia 



Arachnitla . . . 



Total . 



Now, when we come to examine the species of Rhynchophora, we 

 shall find that while the three localities in western Colorado and Wyoming 

 share a nninher of forms in commim, lutt a .sing-le species fonnd at Floris- 

 sant occnrs in either of the others. To give the precise figures : From 

 Florissant 116 species have been obtained; from the Roan nKnintains 40, 

 of which it shares f> with GreiMi river and 7 with White river, besides 6 

 others common to all three localities, together nearly half its fauna (19 sp.); 

 from the White river 23 species, of which it shares 2 with Green river and 

 7 with the Roan mountains, btisides the G common to all, or nearly two- 

 thirds its fauna (IT) sj).); and from Green river 3D species, of which it 

 shares 2 with White river and (! with the Roan mountains, besides the 6 

 common to all, or more than one-third its fauna (14 sp.). These facts, with 

 the held evidence, a,])pear to show tjiat the three principal lo(%alities in west- 

 ern (Joloratlo and Wyoming arc deposits in a single body of water, the an- 

 cient Gosiute lake, as it was called by King. The absolute separation, 

 in speciific forms, ])etween the fauna of these deposits and that of Florissant 

 must be indicative of a distinction greater than that of mere geographical 

 position, for the Roan mountains are about equally distant from Green 

 river and Florissant. It is clearly an indication of a difference in age, 

 thougli they have usually been reganled as occupying similar horizons. In 

 the following jjages I have referred to the species regarded as belonging to 

 the Gosiute lake as the Gosiutk fauna whenever it has been desirable to 

 speak of them in conimon; and in contrast I have called the fauna of Flo- 



