214 ZOOLOGICAL GARDENS. 
nocturnal animals in which the faculty of vision is 
capable of being exercised through the medium of a 
comparatively small proportion of light. Such animals 
are necessarily incapable of bearing the full blaze of 
day, which soon becomes painful to their eyes, thus 
compelling them to close their pupils to such an extent 
as to render their vision very imperfect. Much of the 
cunning suspiciousness of manner for which the Fox is 
notorious is evidently due to this very circumstance ; 
his attitudes and motions necessarily partake of the 
uncertainty of his sight, and he appears to be most 
cunning when he is in reality most short-sighted. To 
shade himself as much as possible from the light, he 
hides himself in burrows during the day, and prowls > 
abroad in full possession of his perceptive faculties 
under the influence of a clouded night. 
But although this distinction of nocturnal and diurnal 
may seem at the first glance to be perfectly natural, a 
shght acquaintance with the animals to which it is 
sought to be apphed will teach us that its value is in 
point of fact not so great as theory would lead us to 
imagine. The Wolf, with a circular pupil, is almost 
equally nocturnal in its habits with the Foxes them- 
selves; and the Jackal, which both in size and form 
makes the nearest approach to the latter, and which 
not only prowls abroad during the night but conceals 
itself like them in burrows throughout the day, has its 
iris formed exactly on the same plan with that of the 
domestic Dog. We cannot therefore consider the habits 
of the two divisions of the genus to be discriminated in 
so marked a manner as to justify their separation by 
means of this character, and still less by means of those 
minor distinctions which have been thrown as make- 
weights into the scale. 
Of these the most striking is unquestionably the 
