ON NOCTURNAL ANIMALS. 3823 
In passing to Mammals, numerous groups are found with 
decide| night tastes. Monotremes, Marsupials, Edentates, Ro- 
dents, Carnivora, Insectivora, &c., all furnish marked examples. 
Some are burrowers, others partially aquatic, others again 
arboreal, no animal profession being unrepresented. 
The Cat tribe is familiar. ‘Their cushioned feet give softness 
of tread; their hearing is exceedingly good, though their outer 
ears may be small. Long bristly whiskers stand out, and as tactile 
organs quickly convey impressions of surrounding objects. Smell, 
too, is acute, though not used equally by all to obtain prey. 
Sight, however, is most relied on. The greenish or sometimes 
reddish glare of the feline eye is familiar, as well as that of 
other nocturnal mammals. This is produced from the tapetum, 
a brilliant irridescent membrane immediately beneath the retina, 
whose finely ribbed surface produces the coloration as an inter- 
ference phenomenon. * ‘lhe ensheathed sharp claws and cat- 
like and muscular development of the body complete organisms 
all highly adapted for the capture by night of often powerful 
prey. ; 
But even in the case of Ruminants which, as a rule, are 
diurnal, night excursions among the vast African herds occa- 
sionally happen. The Grysbok during the day hes hid in reed- 
beds, and regularly feeds at night. 
The Elephant and the T'apir are often night-roamers, want of 
water being a chief incentive with the former; its great ears as 
tactile organs are then useful in treading in the gloom of the 
forest. 
The Star-nosed Mole (Condylura) and the Urotrichus may be 
cited as instances where the lengthened nose, having fringed 
processes of a tactile kind, supplies this deficiency of sight. 
Among the entire range of nocturnal animals none exhibit so 
strikingly, or in so high a degree, the diffused sense of touch 
(referred to when speaking of the very lowest animal forms) as 
the Bats (Chiroptera). So accustomed are we to associate them 
with the dusk that when the writer once saw, in Central Africa 
during the middle of the day, a flight of literally myriads of great 
Fruit Bats, he was as much astonished at the diurnal spectacle as 
* There are two forms of tapetwn—lst, cellular, as found in fishes and carnivora, 
whose cells contain lime-crystals in the former, seldom in the latter; 2nd, fibrous, 
as found in many other mammals, 
