1897.] NATURAL SCIENCES OF PHILADELPHIA. 521 



classed those relating to animal locomotion. In 1869 appeared his 

 Outlines of Comparative Anatomy and Medical Zoology, a com- 

 pend of his lectures delivered in the University of Pennsylvania as 

 Professor of the branches treated of. The concise character of this 

 little book, its simplicity of classification and treatment, and its 

 suggestiveness to the student in original research, distinguish it from 

 ordinary text books, and it may still serve as a valuable guide to 

 instructors in anatomy. 



Notes on the Conformation of the Mammalian Skull and Studies 

 in the Facial Region, also record observations indicating the special 

 studies which Dr. Allen had been conducting previous to the year 

 1875 and which were bringing him into prominence as an anatomist. 



In his studies of animal locomotion Dr. Allen deserves special 

 notice, standing as he does quite alone in his discussion of Prof. Muy- 

 bridge's instantaneous photography of animals in motion. This 

 work was performed at the request of the University of Pennsylvania. 

 He had previously studied anatomically the limbs of the mammalia, 

 notably the wings of bats, with a similiar purpose in view. His 

 paper was modestly entitled Materials for a Memoir on Animal 

 Locomotion. On this unpretentious basis the whole essay is largely 

 conducted, no theories or generalizations being indulged in where a 

 more imaginative writer would have felt at liberty to roam at will. 

 He confined his speculations on animal locomotion, as in his previous 

 work, chiefly to practical suggestions for future investigation. 



In connection with this work we find several examples of newly- 

 coined words and technical terms called for by Dr. Allen's studies 

 in minute anatomy. Without such additions to nomenclature a new 

 branch of technical study such as the one undertaken by Muybridge 

 and Allen could not be intelligently, and at the same time concisely, 

 presented. 



In 1884 Dr. Allen published his System of Human Anatomy, 

 a quarto volume of eight hundred pages, profusely illustrated, and 

 representing an amount of learning and labor far out of proportion 

 to its popularity and financial success. 



His Distribution, of Color Marks in the Mammalia which appeared 

 in the Proceedings of the Academy in 1888, is the most important con- 

 tribution to the literature of the subject yet published by an Amer- 

 ican author. He states his " main object has been to contemplate 

 color marks as the result of nutritive processes, controlled by recog- 

 nized biological forces both in health and disease." The paper is a 



