KNuwLTuN.] BIOLOGICAL CONSIDEEATIONS. 95 



already .said, "Among- liyino- .species this appears to approach most 

 closely to P. halsamifera caridlcans. It differs in being much more 

 obtuse, in having- a more marked serrate border, and in the stronger 

 nervation. The relationship is, however, quite marked, the two leaves 

 being of the same type, but with strong specific differences."^' 



The genus Salix is represented ])y eleven forms, all but one of which 

 {S. Sc/u'nij}eri) are confined to the upper l)eds. Several of the species 

 included are represented liy single and often more or less doubtful 

 specimens, while others are represented by numerous individuals. 

 Thus S. pseudo-at'gentea is very al)undant. It closel}' resembles the 

 living -6'. argentea, whence its name. Sallx perplexa, to which is 

 referred a dozen or more specimens, is very similar in general appear- 

 ance to certain forms of S. Behhlana^ a species now widel}' distributed 

 throughout the Rocky Mountain region. The Myricacea3 are repre- 

 sented by two species, both of which are described as new. Of these, 

 M. oregoniana is verj^ closely related to M. caUicomsefolia Lesq., a 

 species very abundant at Elko station, Nevada, and Florissant, Colo- 

 rado. The other species, Myrica ? 'personata., is whoU}^ unlike anything 

 previously described from the John Day region, and may not belong 

 to this genus. 



The JuglandacetB are richly represented, both Juglans and Hicoria 

 being present, the former with eight forms and the latter with three. 

 The species are rather widely distributed, occurring in the older, mid- 

 dle, and younger plant-bearing beds of the region. Perhaps the most 

 interesting form is Lesquereux's Juglans oregoniana^ which has long 

 been supposed to have come from the Auriferous gravels of California, 

 but which is now known to have come from the Mascall beds at Van 

 IIorn\s ranch. Quite a number of additional specimens have been 

 found recently, and, with the exception of being slightly smaller, they 

 agree well with the type form. One of the specimens described by 

 Lesquereux as Rlias Bendlrei has been referred to this, as also my 

 J. hcsperia,^ from the Paj^ette formation of Idaho. 



Judging from the remains, Hicoria was rather rare, for onh^ a few 

 specimens have been found. 



The famil}' Betulaceaj, so far at least as regards individual leaves, is 

 the dominant family of the flora. It is represented ])y Carpinus, 

 Cor3dus, Betula, and Alnus, each, except Corylus, with several well- 

 marked species. 



The Clarno formation, or the beds at Bridge Creek and allied locali- 

 ties, seems to have witnessed the culmination of the Betulaceaj in the 

 region, for, with the exception of two or three doubtful forms, all the 

 species are conffned to it. 



Carpinus is represented by numerous leaves, which are referred to 

 C. hetuloides at Bridge Creek, while two more or less questionable 



"Eighteenth Ann. Kept. U. S. Geol. Survey, Pt. Ill, p. 726. 



