170 EDWARD B. POULTON. 
bilaterally but radially symmetrical, while the succession is 
probably asymmetrical. In these characters and in the general 
appearance the individual smaller hairs are not scale-like, but 
resemble those of Mammalia generally. 
(2) The inner root-sheath has about the same relative size 
aud the same appearance as that of Mammalia generally. 
(3) The bulb and papilla are both very long and narrow, 
but apparently not so remarkable as those of the large 
hairs. 
(4) The hair is developed in a tube open to the surface. 
(5) The fact that the bundles of small hairs reach the surface 
by a common follicular mouth is probably shown by the mode 
of development to be a comparatively recent feature of no 
ancestral significance. , 
Comparing these features of the large and small hairs, we 
may omit the last-mentioned characteristic of the latter, which 
is probably unimportant. There is similarity in the most im- 
portant point of all—development in open tubes ; but in every 
other respect there is divergence, and always of such a kind as 
to bring the small hairs nearer to those of mammals generally. 
Furthermore, the characters which separate the large hairs from 
those of other mammals are, as I hope to show in all cases, 
characters which suggest homology with one or other of the 
epidermal structures of the higher Vertebrate Classes. 
V. Tue Homotociets AND OrniGiIn oF Mammatian Harr. 
1. Historical; by W. Blaxland Benham, D.Sc., &e. 
There are two main suggestions as to the relation of hairs to 
other Vertebrate epidermal structures : 
(1) The first is that hairs are homologous with the scales of 
reptiles and the feathers of birds. 
(2) The second regards them as not homologous with these 
structures. 
In the latter case two other epidermal structures have been 
suggested as the ancestors of hairs: —(@) Maurer would derive 
hairs from epidermal sense-organs of fishes and Amphibia; (6) 
