98 
POPULAR SCIENCE REVIEW. 
Also a new genus of Porcine animals allied to Elotherium (Pomel), and 
Helohyus (Marsh), but differing from them in having a premolar less ; the 
last lower molar has a distinct posterior lobe. This genus, according to the 
author, affords an interesting example of an extinct form outside of the 
ancestral line which terminated in existing pigs. The species, Parahyus 
vagus, which was about the size of the existing Wild Boar, is from 
Wyoming. 
These pigs were probably persecuted by a carnivore about the size of 
a large wolf, whose remains are found in the same deposits. In its general 
characters this animal, which Professor Marsh calls Dromocyon vorax, closely 
resembled PLycenodon. It had apparently only four lower incisors, and seven 
lower molars, on each side, the last very small. The top of the skull had an 
enormous sagittal crest. Another form, belonging to the peculiarly American 
order Tillodontia, is described as Dryptodon crassus, and appears to have 
been about the size of a tapir. This is from New Mexico. (“ Silliman’s 
Journal,” Nov. 1876.) 
A new American Crinoid. — u Silliman’s Journal ” for July states that 
among the many interesting fossils recently received from the West by the 
Yale College Museum, is a new Crinoid from the cretaceous of the Uinta 
Mountains and of Kansas. No Crinoids from the American cretaceous have 
hitherto been described, and for the discovery of this species we are 
indebted to Professor 0. C. Marsh, who has done so much to bring to light 
the geological treasures of the West. The Crinoid in question belongs to 
the group Astylidse, or free Crinoids, and, as suggested by Professor Marsh 
in his earliest paper on the Geology of the Uinta Mountains, is allied to the 
genus Marsupites of Miller. From that genus, however, it differs widely in 
the number and arrangement of its plates, in having apparently ten arms, 
and in other characters ; and it is possible that an examination of additional 
material may show it to be the type of an entirely new group. This point, 
however, cannot at present be determined. The species is named TJinta- 
crinus socialis. 
Origin of the Dolomites of the Tyrol. — An important essay on the above 
subject has been written by Drs. Dolter and Hornes. It contains a full 
review of the literature of the subject, with a discussion of the various 
theories which have been proposed to explain the existence of the great 
strata of dolomite. The results of an extended chemical examination of the 
dolomites of the Tyrol by Dr. Dolter are given, embracing a considerable 
number of analyses. The authors come to the following conclusions, con- 
firming in part the results of some earlier authors : — (1). A large number of 
extensive strata of limestone, weakly dolomitic, have been deposited imme- 
diately through the instrumentality of organic life in the ocean. (2). Some 
minor occurrences of normal dolomite are due to subsequent metamorphosis, 
through the introduction of carbonate of magnesia. (3). The larger part of 
the dolomites, whether more or less rich in magnesia, have been formed from 
the lime secretions of sea animals through the action of the magnesia salts 
contained in the sea-water (especially chloride of magnesium). Subsequent 
local differences have been brought about through circulating waters, dis- 
solving out and concentrating the magnesia at different points. 
