156 THE AMERICAN NATURALIST.  [Vor. XXXIV. 
where the cells have been derived from two different species, the 
specific characters of the cells remain distinct. G.H.P 
Note. — No. 3 of Vol. XV of*the Journal of Morphology contains : 
« Studies on the Maturation, Fertilization, and Cleavage of Thalas- 
sema and Zirphza," by B. B. Griffin; “On the Blood-Plates of the 
Human Blood, with Notes on the Erythrocytes of Amphiuma and 
Necturus," by G. Eisen ; * The Phosphorescent Organs in the Toad- 
fish, Porichthys notatus Girard," by C. W. Green; ‘On the Species 
Clinostomum heterostomum," by W. G. MacCallum ; and “ Mitosis in 
Noctiluca miliaris and its Bearing on the Nuclear Relations of the 
Protozoa and Metazoa," by G. N. Calkins. 
GEOLOGY. 
The Absaroka Range of the Rocky Mountains. — In a presiden- 
tial address before the Geological Society of Washington,’ and in the 
Absaroka Folio of the United States Geological Survey,? Mr. Arnold 
Hague has presented the results of many years’ field work in a region 
that contains for vulcanologists problems of extraordinary interest. 
The Absaroka Range forms the mountain barrier to the east of the 
Yellowstone plateau, and is composed chiefly of horizontally stratified 
volcanic flows and breccias thrown out from vents, the location of 
which is not marked by conical volcanoes or even by any positive 
trace which would show that such volcanoes existed. Thicknesses 
from two thousand to five thousand feet of these lavas are deeply 
trenched by streams draining the eastern face of a range which 
marks in a sense the eastern escarpment of the great plateau that 
forms the Yellowstone Park. Early breccia and basalt sheets over- 
laid by late breccias and basalts make up the mass of these lavas. 
The only interruptions to their horizontal continuity are massive 
bodies of intrusive rock that invaded the lavas at two distinct 
periods. i 
Evidence of the age of the lavas is derived from the contained 
plant remains and from the old topographies which underlie them. 
The accumulation of volcanic material rests unconformably on rocks 
1 Hague, Arnold. Early Tertiary Volcanoes of the Absaroka Range. 
2 Folio No. 52, Geologic Atlas of the United States, Crandail and Ishawooa 
Quadrangles. Washington, 1899. 
