482 : Recent Literature. [ ZOE 
A systematic classification giving the distinctive features of each — 
class and order follows, the account closing with a few general re- 
marks on the life and history of the group in question. Although 
dealing primarily with anatomy, the external form, habits and gen- 
eral classification of animals are by no means slighted. —_C.A.K. 
Journal of Morphology, V1, 1-360. Vertebrate Cephalogenesis. 
Il. A Contribution to the Morphology of the Vertebrate Ear, with 
a Reconsideration of its Functions. By Howarp Ayers. In this 
work a lengthy and exceedingly important investigation of the em- 
bryology, morphology and physiology of the cordate ear is pre- 
sented. The author has made an exhaustive examination of a great 
number of representative types, and. asa result, revolutionizes many 
of the generally accepted ideas, both of the development structure 
and functions of many of the parts of the ear. The work is illus- 
trated with twelve plates and a number of diagrams and figures. 
Mr. Ayers concludes from his investigations that the vertebrate ear 
is not related phylogenetically to the invertebrate, but is formed by 
the union of two sense organs—the superficial canal complex. He 
finds a close connection between the ear of the alligator and of 
mammals, and considers that the organ of Corti of the latter is a 
direct descendent of the organ of Corti in the former. This modi- 
fies the position of birds in the scale, so far as the morphology of 
the ear is concerned. The author says: “ Having found, from my 
Own investigations, in three groups of birds — Rasores (Gallus), 
Columbinze (Columba), and Passeres (Mimus)—that the develop- 
ment of the cochlea is not so far advanced as in the hydrosaurian 
reptilia, it will be necessary to change the view advocated by Hasse, 
according to which the saurian reptilia stand as transitional forms 
between the amphibia and the lower reptilia and the birds, for it is 
obvious that in cochlear anatomy the birds hold a place apart from 
the direct line of descent as typified in the mammalian cochlea.’’ * 
Mr. Ayers’ generalizations with regard to the development of the 
ear are of great importance. “Although ontogenetic evidence,’’ he 
says, T ‘seems to lead to the conclusion that the auditory organ 
arose by the invagination of ‘a single superficial sense organ, it is by 
no means certain that this is true, for there are certain facts of com- 
parative anatomy and certain phylogenetic considerations which 
* P. 227. t P. 231. 
