No. 387.] REVIEWS OF RECENT LITERATURE. 265 
Gegenbaur builds on his former arrangement: under the head of 
integument we find chapters on the epidermis, the corium, and the 
pigment; under organ-formation of the integument are placed in 
sequence horny structures, skin glands, mammary organs, scales and 
feathers, and hair; finally there is a chapter on the dermal skeleton. 
While this classification may not be ideal, it has the great advantage 
of bringing together those organs which are most likely to form nat- 
ural series. It is obviously much more in accord with the traditions 
of comparative anatomy to consider, for instance, integumentary 
glands under one head than to scatter them through a descriptive 
account of the integument of different groups of vertebrates. In this 
respect Gegenbaur has made a positive advance, and the shortcom- 
ings which his system may eventually show will doubtless be found 
to have been the result of what is at present undiscovered rather than 
of any lack of appreciation on the part of Gegenbaur as to what the 
comparative method implies. 
The volume is so replete with material which, if not exactly new, 
is at least first brought together in compact form, that it is practi- 
cally impossible to review it in detail. It is interesting, however, to 
„Observe the position assumed by Gegenbaur on several important 
questions with which he has been closely associated in the past. 
Thus, on the relation of the marsupium to the mammary pockets 
he maintains his original opinion that these organs are essentially 
distinct, although Klaatsch has recently shown that it is quite 
possible that the marsupium has arisen by a fusion of mammary 
pockets. On the question of the origin of the lateral appendages 
Gegenbaur stoutly defends his original contention that these parts 
probably represent modified gill-arches, his general argument being 
that it is safer to assume that the lateral appendages have come from 
gill-arches about which we know something than it is to suppose them 
derived from a continuous lateral fin about which we know little or 
nothing. In matters of theory the volume is strikingly conservative, 
and this conservatism is in some respects an advantage. ‘Thus, in 
the treatment of the crdnial nerves the parts are fully and well de- 
scribed, but the account is not concluded with a tabulation in which 
some more or less imaginary segmental value is assigned to each 
nerve. In this respect Gegenbaur’s treatment of the subject seems 
to us wisely out of style. 
It would deservedly be a thankless task to point out the small in- 
accuracies which this, like all other books, contains. The omission 
of a pisiform bone from the carpus of the snapping turtle (p. 529), 
