Dr. J. E. Gray on the Wart- Hogs. 455 
XLV.—feply to Dr. Sclater on the Wart-Hogs. 
By Dr. J. E. Gray, F.R.S. &c. 
THE only reply that I think it desirable to give to Dr. Sclater’s 
observations in the preceding Number, as regards the Wart- 
hogs, is to request such readers as take sufficient interest in 
the question to read my two former notes on the subject, which 
were called forth by Dr. Sclater’s remark in the ‘ Proceedings 
of the Zoological Society,’ and then to read his observations ; 
and I feel sure that they will think them as sophistical and 
unlike a scientific communication as his paper in the ‘ Pro- 
ceedings,’ in which he figured a head of an adult male and of . 
a young female, without stating their age or sex, as ^ illus- 
trative of the external difference between these two wart- 
hogs” (P. ethiopicus and P. ZEliani). It has yet to be 
proved that the whole difference between the two heads does 
not depend upon the age and sex of the animals whose heads 
are figured. The heads are known to change in form, an 
very probably the hair on the ears becomes more developed, 
as the animal reaches the adult age; and it is one of the 
scientific uses of the Zoological Gardens to observe such facts. 
And I think it a pity that Dr. Sclater did not wait until he 
could inform us whether this was the case, more especially as 
the nakedness of the ears is not the character given by Rüp- 
` pell of P. Aliant; and if it should have been found that when 
` the animal reached the adult age it had such ears as are figured, 
it would have been the addition of an important fact to our 
knowledge-of the genus, the existence of a second species of 
which would give me great pleasure. 
It is true that the observations of “ M. F. Cuvier, Van der 
the o ce of examining when they made their observations 
i h were all [e 
patiently and repeatedly to discover if I could divide them 
into two kinds, according to the characters which the natu- 
ralists quoted had used to separate the two presumed kinds; 
and I came to the conclusion that it was impossible to sepa- 
