THE ZOOLOGIST. 
THIRD SERIES. 
Vou. IIT.) AUG USE. 187 9. [No. 32. 
ON NOCTURNAL ANIMALS.« 
By James Murir, M.D., LL.D., F.L.S. 
A CONSIDERATION of all that is known respecting the habits 
and manifold peculiarities of those animals whose active phases 
of life come under the denomination “nocturnal” is manifestly 
impracticable within the limits of the present paper. A selection 
of instances in point, therefore, is unavoidable. In this case 
preference is given to the Vertebrata, inasmuch as many are 
familiar objects in our public gardens and travelling menageries. 
Scarcely one of the subkingdoms and classes of animals can 
be named but has a subordinate group, or more often a limited 
section, or species of a group, which, in contradistinction to its 
fellows, exhibits abnormal habits and manifests a preference for 
darkness over daylight. Very frequently there is associated with 
this exceptional habit some diversity in organs and subsidiary 
structures adapted to the creature’s particular mode of life. Still 
occasionally where no pronounced structural differences are 
observable one is at a loss to account for singularity of habit. 
Something, therefore, which is not always apparent may underlie 
this tendency to variation. 
Can it be that one or more dominant though hidden forces 
are at work that at least would partially explain the enigma? Or 
* This article is based upon a lecture delivered by the writer during the present 
summer, in the course of “ Davis Lectures” at the Zoological Society’s Gardens. It 
has been modified, however, in some respects, and especially in the elimination of 
much that was stated with regard to the lower forms of life. 
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