140 Animal Life 
Sometimes this lemon ground is almost 
ereenish by the admixture of gray or brown 
hairs. On this light ground are scattered 
many irregular spots, bluish-black with the 
sheen of the hair. The hind limbs incline 
more to umber brown. The strong vibrissa@ 
are white. In some specimens the spots are 
very thick on the back, and are brownish. 
Some examples of the common seal are 
almost black all over. Others, agai, are 
a greenish-yellow, with only a few black 
spots. The large eyes are one uniform tint 
of deep bluish-brown.” 
Is 
A CORRESPONDENT writes to us as follows: 
New Contributions =>!nce attention has been 
to the Study of directed on several occasions 
ALLSTON COO ETIONS 5 your journal to animal 
coloration, your readers may hke to hear 
something of two new contributions to this 
subject. In ‘The Field’ of October 17th, 
Mr. Llydekker, amplifying an investigation 
recorded in earlier articles (reproduced in 
‘Mostly Mammals’), feels himself justified 
in asserting that in mammals a_ seasonal 
change of colour is correlated with the fall of 
the leaf, and does not take place im tropical 
and sub-tropical species. And he suggests 
that the same law may hold good in the 
case of birds. In inammals of the temperate 
zone, as well exemplified by the roe-deer, 
the change is very generally from some 
shade of chestnut or rufous-brown in summer 
to grey or brownish-grey im winter. It is 
also pointed out that in Arctic and sub-Arctic 
mammals, the change is from grey or grey- 
brown in summer to white in winter; so 
that these changes seem to be merely an 
extension of those which take place in 
mammals of the temperate zone. Further, 
a certain number of tropical or sub-tropical 
Species, such as the males of the Indian 
black-buck and of Mrs. Gray’s water-buck 
of the White Nile, exchange the typical 
rufous tint when fully adult for a sable 
livery (this, of course, not being a seasonal 
change). Hence it would seem that all 
these changes form part of a connected 
series; rufous, or bay, being the primitive 
type, or starting point. As to the reason 
for this prevalence of rufous as the summer 
coat of so many temperate maminals and 
the permanent livery of tropical -kinds, it 
is suggested that its power of resisting 
the bleaching effects of sunlight may be the 
most important factor. 
“The second contribution is by Mr. W. L. 
Power, of Chicago, who gives in ‘ Decennial 
Publications” an exquisitely-coloured plate 
showing the gradual development of a deep 
chestnut colour, variegated with black mark- 
ings, in a long-horned beetle. Starting 
from a pure white pupa, we notice the first 
appearance of colour in the head, whence it 
extends in successive stages backwards till 
the deep adult tints are attaimed. Dark 
spots and stripes are likewise shown to make 
their appearance in a precisely similar manner 
in another kind of beetle. 
“Colours of this type are the result of 
pigment developed in the dermal tissues of 
the insects, and the various markings (when 
present) correspond to a great extent with 
the subjacent vital organs. Moreover, they 
are largely due to the nature of the inteeu- 
ment (or ‘chitin’) itself, which has a 
marked tendency to turn brown as it hardens. 
Hence the prevalence of brown and yellow 
in beetles, cockroaches and earwigs, which 
display the typical ‘ chitmous,’ or horny 
integument. Moreover, this type of colora- 
tion is evidently very ancient — probably, 
indeed, as old as insects themselves. 
“On the other hand, many of the more 
specialised insects, such as peacock and red 
admiral butterflies, develop a totally different 
type of coloration, which in place of being 
situated in the integuments, has its origi 
in the minute scales (or modtfied haus) 
with which the latter is clothed. More- 
over, since it has no sort of connection with 
the vital organs, or with the brown chitin 
of the integument, it can run riot in the 
matter of brilliant hues and of eccentricity 
of pattern. Hence we have an explanation 
of the reason why butterflies are so much 
more elaborately and gorgeously coloured 
than beetles, so far at Jeast as the pigment 
colouring of the latter 1s concerned; the 
metallic tints of many beetles being due, of 
course, to the prismatic breaking-up of heht, 
and not to pigment at all.” 
