6 NATURAL SCIENCE. Jan., 
THE SQuARE-MoUTHED RHINOCEROS. 
Ir has been considered that the square-mouthed, or so-called 
White Rhinoceros (R. sius) is already extinct. Recently, however, 
Mr. F. C. Selous has written to our contemporary, the Field, to say 
that a few ofthese magnificent animals still survive in a remote corner 
of Mashonaland. One of these last survivors has already been killed, 
with the view that its remains should find their way to the British 
Museum. We trust, however, that the authorities in Mashonaland 
will take care that the others are not molested, and may be allowed a 
chance of propagating their species. 
We may take this opportunity of mentioning that although most 
zoologists have recognised the extreme specialisation of the molar 
teeth of this species, as exemplified by their very tall crowns, and the 
flat plane of wear of their grinding-surfaces, yet it does not appear to 
have been noticed that they differ from those of all other living 
Rhinoceroses by the presence of a thick investing coat of cement. 
Not only does this cover the outer surface of the tooth, but it likewise 
fills up both the main and the posterior valleys. Indeed, the molars 
of this species bear almost the same relationship to those of the 
Sumatran Rhinoceros as is presented by the molars of the Horse to 
those of the Anchithere. 
In the extinct Woolly Rhinoceros (R. antiquitatis) the cement is 
present to a less degree in the molar teeth, which are of the same 
general structure; while in the allied R. platyrhinus, of the Siwalik 
Hills of India, there was, probably, also a certain amount of this 
constituent. In both these extinct species the teeth do not, however, 
appear to attain the extreme specialisation of the square-mouthed 
Rhinoceros, and it is accordingly difficult to regard the latter as 
representing a genus apart from the one including all the other 
existing species, which we should otherwise have been disposed 
to do. 
THE SCIENCE OF GROWTH. 
READERS of a recent article in NATURAL SCIENCE on the Anatomy 
and Development of the Brachiopoda, who were appalled by certain 
strange and fearful words, such as ‘‘nepionic,” ‘‘ ephebolic,” and 
‘‘nostologic,” will be interested to learn that those terms have just 
been elucidated and improved by S. S. Buckman and F. A. Bather 
in a paper entitled ‘*‘ The Terms of Auxology ” (Zoologischer Anzeiger, 
November 14 and 28, 1892, pp. 420 and 429). Growth and change, 
as the authors observe, do not stop in an animal when the embryonic 
stage has been passed; nor is the study of later stages of less impor- 
tance than that of the earlier. Thus has arisen a new science, of 
which embryology is only a part; and, as was inevitable, definite 
names have been given to the various post-embryonic stages. Un- 
fortunately, the names used were not only open to serious objection 
