522 THE AMERICAN NATURALIST. (VoL. XXXIX. 
Distribution of Salicacee in Cretaceous of United States. 
POPULUS. 
Lower. Middle. Upper. 
Populus berggrent ; x x 
hyperborea x 
stygia x 
mutabilis Her x ; 
melanarioides 
wardii 
AARAA RX 
mutabilis ovalis ? - 
apiculata : X 
aristolochioides 
auriculata x 
cordifolia 
elliptica x 
X X 
harkeriana 
latidentata x 
kansaseana x 
longior x 
xx 
leuce 
microphylla 
potomacensts 
protozadachi 
rectinervata 
trinervis 
sp. 
XXXXXXX 
sp. 
Populites tenuifoitus 
cyclophylla 
elegans 
lancastriensis 
litigiosus 
microphyllus 
probalsamifera x 
XXXXXX 
X X 
t 
winchelli 
Populophyllum crassinerv 
hederaforme 
reniforme 
«| xxx 
Species 42 

Percentage distribution : 18.1% 43.1% 38.67; 

