ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
533 
work of sixty-seven pages, illustrated by ten plates, on ‘ A Flora and 
Fauna within Living Animals,’ of the botanical part of which Dr. Gray 
said in this Journal, “ A contribution of the highest order, the plates 
unsurpassed if not unequalled by anything before published in the 
country.” In 1879 appeared his large quarto volume on the freshwater 
rhizopods of North America, containing forty-eight coloured plates, the 
material of which was in part collected during two seasons in the Rocky 
Mountain region. As a portraiture of the doctor over the little member- 
less species, we quote from his concluding remarks : — “ The objects of 
my work have appeared to me so beautiful, as represented in the illus- 
trations, and so interesting, as indicated in their history which forms 
the accompanying text, that I am led to hope the work may be an 
incentive, especially to my young countrymen, to enter into similar 
pursuits. ‘ Going fishing ? 5 How often the question has been asked by 
acquaintances as they have met me, with rod and basket, on an excursion 
after materials for microscopic study. £ Yes,’ has been the invariable 
answer, for it saved much detention and explanation ; and now, behold, 
I offer them the result of that fishing. No fish for the stomach, but as 
the old French microscopist, Joblet, observed, ‘ Some of the most remark- 
able fishes that have been seen, and food-fishes for the intellect.’ ” He 
delighted in his work because he knew that there was no fact in con- 
nection with the structure and functions of the simplest living things 
that was not profound and comprehensive, that did not reach up through 
all species to the highest. The vertebrates described by him were 
mainly fossil species. Dr. Leidy has the honour of having opened to 
geological science a general knowledge of the remarkable mammalian 
fauna of the country, and especially that of the Rocky Mountain region. 
Species had been before described, but through him the general range of 
North American species began to be known. In 1847 he published on 
the fossil horse ; in 1850, on the extinct species of the American ox ; 
1852 and 1854, on the extinct Mammalia and Chelonia from Nebraska 
Territory, collected during the survey under Dr. D. D. Owen ; in 1855 
on the extinct sloth tribe of North America; in 1869, on the extinct 
mammalian fauna of Dakota and Nebraska, a thick quarto volume 
published by the Philadelphia Academy of Sciences, based on materials 
that had been gradually and continuously accumulating for the last 
years; and in 1873, contributions to the extinct fauna of the Western 
Territories, making the first quarto volume of the Hayden Survey. The 
last two works mentioned contain over eight hundred pages of text and 
nearly seventy of plates. Besides these large works numerous short 
papers from time to time appeared. 
Dr. Leidy retired from this field when questions of priority began to 
start up, it being no part of his nature to quarrel, and having the firm 
belief, as he said, that the future would award credit where it was 
deserved. His work among the fossil vertebrates extended also to fishes, 
batrachians, and reptiles of different geological periods. Dr. Leidy ’s 
zeal never flagged ; his labours came to an end only with his sudden 
death. Eight days before it he delivered his last University lecture. 
Beginning original work before he was twenty, his published papers 
and larger books continued to appear through half a century, and number 
over nine hundrod. As is well said in one of the many tributes to him 
