Bibliographical Notices. 205 
good as have the patient investigations of various naturalists into 
the structure and life-history of a given type. 
Those who write works like these are, whether they think of it 
or not, raising for themselves monuments of intelligent and well- 
directed industry which will last long after the contents of many 
Transactions and Journals have been digested, and have become 
themselves neglected. 
So much is said against and so little is said for the opportunities 
which are given to zoologists in this country, that we cannot re- 
frain from pointing out that Mr. Dobson returns his especial thanks 
to Sir W. Muir, who, at the time of the writing of his preface, was 
the enlightened head of the Army Medical Department. 
The two parts of the Monograph now before us deal with six 
families :—the Erinaceide, Centetide, and Solenodontide ; the Pota- 
mogalidz, Chrysochloride, and Talpide. In addition to a detailed 
anatomical examination of a number of typical forms, all the species 
are dealt with in the fashion of a systematic zoologist ; twenty-two 
plates, with a number of woodcuts, illustrate the text, and speak for 
the care that has been given to the supervision of their production. 
One would require more than the usual calm superiority of a 
reviewer to closely criticise the work in these two parts; we pro- 
pose rather to direct the attention of the reader to one or two points 
which seem to have been treated in a novel manner. 
No one has ever studied the Mammalia without being attracted to 
their dentition; yet few seem to have studied it with profit; and 
even those who have made important discoveries are still in doubt as 
to some considerable questions of homology. We are glad to see 
that Dr. Dobson recognizes the value of formule in the manipulation 
of such questions ; and, indeed, he does not recognize it merely, he 
demonstrates it. In four lines he shows us by an ingenious method 
his views as to the homologies of the teeth in Gymnura with the 
typical dentition of a diphyodont heterodont mammal, and those 
of the hedgehog :— 
GYMNURA. 
* 6=(2a+26 +2c) c 2=(d+d) 8=(2e+2f+29+2h) 6=(i+2j7+2k) . 
* 6=(2a'+20'+2c!)? ~* 2=(d'+d')’ [aes 8= (Qe! +2f'+29/+2h')? ~ * 6=(2i+2j'+2k') 
ERINACEUS. 
- 6=(2a+2b+2c) 2=(d+d) 6=(2f+29+2h) 6=(2i4+2j+2k) | 
: 4=(2a'+20') ’ * 2=(d'4 da’)? ‘ 4=(2f'+2h') p) U 6= (2 +2)’ +2k')° 
If we are to retain the term ‘“‘ canine” at all, we shall perhaps 
do well to follow Dr. Dobson and keep to the old definition that the 
“canine” in the lower jaw is the tooth that comes in front of the 
upper canine when the jaws are closed ; on the other hand we have 
to remember that the connotation of canine is almost as much phy- 
siological as homological, and in the mole the “ caniniform” tooth 
shuts behind, and notin front of, the upper canine. Mr. Dobsonis, 
at any rate, bolder than Mr. ©. 8. Tomes, who some years ago 
refused to write out the dental formula of the mole. 
The writers of zoological text-books must bear in mind Microgale 
