284 ROBERT J. TERRY 



with the notochord in its later history. In the ethmoidal region 

 interest has been centered upon the skeletal structure of the 

 floor of the nose. Harvey, Broom, and Zuckerkandl have each 

 contributed valuable descriptions of the cartilaginous frame- 

 work about Jacobson's organ and the incisive ducts in cat. 



In the present paper the monographs on the anatomy of cat 

 by Strauss-Durckheim, Wilder and Gage, Jayne, and Reighard 

 have been very helpful, as have those works of a more general 

 scope, but including the cat, by Chauveau, Paul Martin, and 

 Weber. Finally should be mentioned those studies, in which 

 cat has offered the material, of head structures other than the 

 cranium which are inseparably connected with the problems of 

 the skeleton, many of which have aided the present investiga- 

 tion. Among these are, specially, Retzius' researches on the 

 ear; Goppert and Corning on the ocular muscles; Peter, Born 

 and Seydel on the nose; Froriep and van Wijhe on the occipito- 

 spinal nerves. 



This paper is concerned with some of the problems of cranial 

 development in mammals, the chondrocranium (exclusive of the 

 visceral skeleton) in cat serving as the material for study. It 

 was the intention to give the descriptive portions of the several 

 cranial regions, as far as possible equal treatment, but to limit 

 the discussion to a few problems upon which some hght was 

 thrown by the structure and development of the cranium in 

 the particular form under consideration. The occipital region 

 was looked to with keen interest as an unworked field for obser- 

 vation, and for any evidence of those processes revealed by 

 Weiss, Gaupp, and Weigner in mammals which indicate a close 

 resemblance to, if not an actual repetition of the steps in the 

 development of the atlas. As stated above, the work on the 

 otic region, hitherto, treats of late embryonic and adult condi- 

 tions. In the present paper, attention has been directed mainly 

 to conditions of early development, such as the origin of the 

 cartilaginous otic capsule, the comparison of the embryonic 

 vestibule with t'hat of reptiles and the theoretical questions 

 concerned with the development of the cochlear skeleton. Con- 

 sideration of questions relating to the development and signifi- 



