1898] NOTES AND COMMENTS 159 
by the expeditions of the American Museum under Dr J, L. Wort- 
man, during 1892 and 1894, from the Oligocene White River Beds 
of Nebraska and Dakota, These present a very large and perfect 
series of skulls, many of them associated with fairly complete 
skeletons, 
Future parts of the monograph will deal with the Aceratheres 
of the American Miocene; the Aceratheres and Rhinoceroses of 
Europe in comparison with those of America, skeletal characters of 
American Aceratheres, and final classification of the Rhinocerotidae ; 
the Amynodontidae; and finally the Hyracodontidae. Professor 
Osborn states that it is his one single purpose “ to establish a sound 
philosophical basis for the morphology of the Rhinoceroses, derived 
from their primitive, parallel, and divergent characters, and leading 
toward the discovery of their origin, phylogeny, and distribution.” 
If the remaining parts of his Memoir are like that now before us, he 
is fairly assured of success. 
On CYCLAMEN 
THE well-known genus Cyclamen is the subject of an exhaustive 
memoir by Dr Friedrich Hildebrand of Freiburg, which has- been 
recently published by Fischer of Jena. The thirteen species are 
almost confined to the Mediterranean region, spreading northwards 
only as far as southern Germany, and eastwards to the Caucasus. 
Cyclamen is a good example of adaptation to the climatic conditions 
prevailing in the district in question. A season of luxuriant growth 
alternates with a season of rest, but the determining factor is not, 
as in higher latitudes, the appearance or disappearance of continued 
frosts, but variation in the amount of moisture. Hence the most 
striking characteristic of this plant is the great tuber, which, like the 
bulb of the lily or the corm of the crocus, enables it to remain alive 
during the dry season, It is interesting to note that an important 
systematic character resides in this highly adapted structure, since in 
some species the tuber protects its contents by a corky layer, in others 
by a felt-like covering of hair, Its early development again is of 
great interest. The nourishment stored in a seed is generally used 
up on germination in the production of one or more green leaves, the 
assimilating organs, by aid of which the seedling becomes an inde- 
pendent organism. Cyclamen, however, has become so impressed 
with the importance of forming a tuber, that it starts even before 
the unfolding of the first leaf, which means that some of the reserve 
nourishment stored in the seed is not used to make leaf-tissue, but 
is passed down the leaf-stalk to form a new reservoir in the short 
stem just above the young root. 
There has been much argument as to the cotyledons of Cyclamen. 
As a member of the primrose family, and, therefore, a dicotyledon, it 
