Reviews — Prof. 0. C, Marsh's Binocerata. 227 



sifle of the foot clearly indicates such a protection. No portion of 

 this covering has been preserved in any of the known specimens, 

 and no foot-prints indicating its form have been discovered in the 

 Eocene deposits in which the Dinocerata were entombed." 



" The size of Tinoceras ingens, as he stood in the flesh, was about 

 twelve feet in length, or sixteen measured from the nose to the end 

 of the tail. The height to the top of the back was about six feet 

 and one-half, and the width across the hips about five feet. The 

 weight, judging from that of existing mammals, was about six 

 thousand pounds. 



" Dinoceras mirabile was about one-fifth smaller. The neck was 

 longer, but, in other respects, the proportions were nearly the same." 



In conclusion the author observes : — " Our present knowledge of 

 the Mammalia, living and extinct, clearly indicates that they must 

 go back at least to the Permian. The generalized mammal of that 

 period, or of still earlier time, was probably quite small, and, in 

 many respects, like an Insectivore. This primitive type would 

 naturally possess all the general characters found in later forms in 

 the various orders of mammals. 



" This generalized mammal would belong to the group named 

 Hypotheria by Huxley, .who has laid a sure foundation for investi- 

 gation in this line of research." 



In a carefully compiled synopsis Prof. Marsh enimierates twenty- 

 nine described species of Dinocerata, of which seven are assigned 

 to Dinoceras, seventeen to Tinoceras, and five to UintatJierium. It 

 contains a reference to every publication in which they have been 

 respectively described or noticed, with the date of publication 

 and the synonym. It is illustrated with thirty-one woodcuts 

 representing what is known of the species, or of some characteristic 

 point in the cranial structure. This Appendix is most valuable 

 for the student of this interesting group of Ungulates, as it enables 

 him at a glance to find the where and the when of all that has been 

 written relating to them. 



Space does not permit us to dwell more fully iipon this most 

 attractive Memoir. The subject of the evolution of the Mammalia 

 is so vast, and so full of interest to the palseontologist, as well as to 

 the zoologist, that Prof. Marsh's volume is sure to be taken up by 

 both and studied with the attention it so richly deserves. It is a 

 pattern of completeness, and may serve as a model for other writers 

 to follow. The author modestly observes that his aim has been to 

 make the illustrations tell the main story to the anatomist. " The 

 text," says Prof. Marsh, " may lose its interest and belong to the 

 past, but good figures are of permanent value in all departments of 

 natural science." The author is, we think, to be congratulated upon 

 the excellence of both text, woodcuts and plates, and we earnestly 

 trust that both life and energy may be prolonged to Prof. Marsh, for 

 many years to come, in which to continue this most splendid scientific 

 work. 



It may not be without interest to our readers to learn that Prof. 

 Marsh has most generously placed a fine series of casts of skulls 



