REVIEWS. _ 39 
would have had some value as showing the variation in respect to 
this ratio that obtains between specimens of the same species. 
But the idea of determining the relative slenderness of two ani- 
mals by the number of times the length of the head is contained 
in the total length of the body, is, to say the least, a novel one to 
me, since slenderness and robustness of form usually involve, as 
is well known, the head as well as the trunk, as a little reflection 
will doubtless at once convince my reviewer. ` That the expression 
‘**form more slender’ of the former [Oulophocine] implies a 
greater relative total length for these animals than the head alone 
_ would indicate,” is an announcement for which I was quite unpre- 
pared. 
In regard to the length of the ear in the two groups, it appears 
that Dr. Gill has also been unfortunate in his generalizations. Ac- 
cording to his quoted measurements, the ear in the longest-eared 
species of: the hair seals (Eumetopias) scarcely equals that of the 
shortest-eared species of the fur seals, but he seems to haye for- 
gotten that the bulk of Eumetopias is several times that of the. 
largest of the fur seals, so that while the ear is absolutely but 
little longer in the fur seals than in the longest-eared hair seals, it 
is relatively very much longer. 
Having said this much in regard to the validity of the charac- 
ters I gave as distinctive of these two groups, I desire to add a 
word in respect to the matter of ‘‘ conservatism.” Dr. Gill says, 
‘t In the case of doubtful species — at least of those which have 
tangible characters, but the value of which may be dubious — some 
naturalists refer such at once to species which they appear in their 
judgment to most resemble, while others — probably most — retain 
them with reserve, awaiting future information. Of the former 
school, Mr. Allen is an ardent disciple, and finding a certain 
range of variation in some known form, he concludes that analo- 
gous variations are only of like value.” In reply to this, I will 
only say that my practice is to never reduce to a synonyme any 
species presenting ‘“ tangible characters,” or even those which ap- 
. pear to have such characters, or where the probability seems to be 
that it may be distinct, though not as yet properly characterized. 
When no evidence of the validity of a given species has been 
advanced, which in the light of present facts can be so considered, 
I deem it subservient to the interests of science to refer them to 
the species to which they seem evidently to belong; as in no 
