INTRODUCTION 3 



shows that there are numerous modifications of the epidermis, 

 and it would appear that some of these are premonitory of the 

 development of the papillary ridges in higher zoological groups. 

 The greater part of the macroscopical branch of the subject 

 consists of detailed description and illustrations of the papillary 

 ridges. The microscopical portion is also shortly described and 

 much illustrated by photomicrographs and drawings from sections 

 of the skin. For this purpose nearly all the specimens have been 

 hardened in alcohol, a few in other preservative fluids, and, in 

 most cases, many sections from each species and from all the 

 main regions of the hand and foot have been made. In all of 

 them careful note has been kept of the position and direction of 

 the sections, so that each illustration may be considered to be 

 correctly " orientated." The more minute microscopical details 

 of the sldn have not been attempted, methods of staining so as 

 to bring out the nerve-endings and nerve fibrils being not necessary 

 for the purpose in view, which is to show the outhnes in a large 

 number of animal forms of the surface of the epidermis and of 

 the papillary layer of the corium. Nearly eight himdred sections 

 in all have been made, and eighty-six species of Mammals and 

 Birds have been examined macroscopically, and, in most cases, also 

 microscopically. The Birds have been taken out of their zoo- 

 logical order, and as being much fewer and of less importance 

 to the subject than Mammals : 



The following have been examined : 



Monotremes. 



Ornithorhjmclius anatinus. 



Echidna hystrix. 

 Marsupials. 



Didelphys azarse. 



Thylacinus cynocephalus. 



Petaurus sciureus. 



Potorous tridactylus. 



^pyprymnus rufescens. 



Petrogale penicillata. 



Macro pus antilopinus. 



Slacropus derbianus. 

 Edentates. 



Myrmecophaga jubata. 



