REVIEWS. 307 
cate affinities, with so many different groups, that he has been obliged to 
place them in a separate order by themselves. ‘ Sycometra compressa 
appears as a sponge stock which bears MUN one and the same cormus the 
mature forms even of eight different genera. 
conclusion Professor Heckel begs all of his readers who may be in 
possession of specimens of calcareous sponges to send them to him for 
examination and comparison. 
THE EXTINCT MAMMALIAN FAUNA OF DAKOTA AND NEBRASKA.* — This 
important work is the final expression, the author informs us, of labors 
extending over a period of twenty-three years, during which the mate- 
rials on which it is based, have been accumulating. Sufficient time has 
elapsed to allow of corrections of first identifications, and we have the 
result in a memoir of much completeness and accuracy in the topograph- 
ical descriptions of the remains preserved in such unusual perfection and 
y Mes 
have seen the light. As it is, the execution both in printing and litho- 
graphy, is a credit to all concerned. 
The species hitherto discovered in the Bad Lands belong to two series 
of strata, determined many years ago by Dr. F. v. Hayden to be Miocene 
and Pliocene respectively. Fossils from these, and a few of Postpliocene 
age are included. derived from the area in question. The whole d 
described is eighty-six, distributed as follows: Carnivora, fifteen; Artio- 
— thirty-four; Perissodactyla, twenty-nine: Rodentia, pus Insect- 
ivora, two. With reference to the relations of the genera and species, | 
we dee the author speak, by quoting his valuable summary at the close of 
the descriptive portion of the work: 
*In comparing the two lists ts representing the North American tertiary essen. mainly 
from the states of Dakota and Nebraska, the quaternary mam: 
mals of the same continent, a remarkable dissimilarity is Sbenived, p the we is also 
a tst esemblance of the former with the tertiary and quaternary mammals of - old 
Miaflo f 
nan. nol 4 one qua rs in the quaternary formation of North America; and of tuünihone 
wenera a of procesy terrestri mammals, ch iefly from is Niobrara River of Nebraska, only 
f Nort eríca, and of these eight three are 
abse nt in the existing fauna of the continent, The ma rsa alluded to as common to the 
pliocene tertiary and the quaternary formations are Canis, Cervus, Dicotyles, Mastodon, Ele- 
p 
It is uncertain how far the s spies es of Canis attributed to the Niobrara pliocene formation 
are peculiar to it. Part of the fossils may be em aternary, or 66 a eae even er remains. 
Of Cervus, part of the specimens referred to it may be of a reversed Bere the antler 
viewed as as pertaining to the same may represe xia a peculiar genus, vnus, subeequen ay extinguished, 
Th 
Ane only 
longed to a quaternary or perhaps a recent species. The remains of the piceo. Mastodon 
be 
f Matat. A Nah i ata TNI " 
> y f the Mammal- 
ian Remains of North America. 
on the Geology of the Tertiaries of Dakota and aka, by Professor F v. Hayden, M. D. 
