22 Proceedings of the Royal Physical Society. 
applied to Mr Mackenzie to assist us in remedying this 
deficiency, and he has very kindly done so by sending both 
a full-grown living beaver, and a foetus taken from the 
mother before birth. In sending a living specimen, Mr Mac- 
kenzie remarked that it would probably ultimately answer the 
purpose of a skeleton, should the climate of Edinburgh not 
agree with the animal's constitution. I had destined it for 
the pond in the Edinburgh Royal Botanic Gardens, where 
Professor Balfour could have given those interested in natural 
history an opportunity of studying its habits at their leisure. 
It might easily have been kept alive if it once had reached the 
gardens. There would have been no difficulty in supplying it 
with birch twigs and branches, its native and proper food ; 
and Mr Mackenzie informs me that it is by no means par- 
ticular in its food, and that if it had the run of the kitchen 
(that is, I presume, the opportunity of selecting what it chose 
from the debris of an ordinary family's table) it would do 
very well. Unfortunately, it never got the chance of trying 
the climate of Edinburgh, nor we the chance of trying experi- 
ments upon it or its food. It reached London alive, but that 
was all. It died next morning. It was, however, carefully 
transmitted to me, and along with the foetus received last year 
was presented by me to Professor Goodsir, who has under- 
taken to make a careful dissection of it, and to communicate 
anything he might think of interest. There are a number 
of points in the internal anatomy on which information is 
wanted, such as the castor, and the glands which produce it, and 
others which might throw light on some disputed (I cannot call 
them doubtful) points in its economy and habits. For instance, 
we know from Hearne, that the usually received notion that the 
animal uses its tail as a trowel to plaster its work, is merely a 
vulgar prejudice, arising from its flapping it on the ground 
occasionally, and more particularly when about to plunge 
ijito the water. Now an examination of the muscles of the 
tail might, were it necessary, throw light upon this point. 
But I imagine that the whole structure and habits of the ani- 
mal explain the use of the tail sufficiently even without ana- 
tomical assistance. On examining its external peculiarities we 
find that its fore paws and feet are short and comparatively 
