THE 
AMERICAN NATURALIST 
VoL. XXXIV. January, 1900. No. 397. 
INTERCENTRA AND HYPAPOPHYSES IN THE 
CERVICAL REGION OF MOSASAURS, 
LIZARDS, AND SPHENODON. 
HENRY FAIRFIELD OSBORN. 
In the course of a recent study of the skeleton of Mosasaurs! 
I was much struck by the uncertainty which prevails in the 
interpretation of the elements entering into the vertebrz of 
the neck. The leading American authorities, Cope, Baur, and 
Williston, differ widely in their descriptions of these parts in 
different papers. The late Professor Baur himself had a per- 
fectly correct notion of the components of the neck, as I learned 
from him in conversation ; but a clear statement of his views is 
not to be found in his published writings. Two of the leading 
German comparative anatomists, Gegenbaur and Wiedersheim, 
fail entirely to recognize clearly the very interesting structure 
of the cervical vertebrae. I was thus led to the comparison of 
the neck vertebra in different members of the Squamata and 
Rhyncocephalia, with most interesting results. 
It appears that zmfercemtra are present in the neck of all 
1 A Complete Mosasaur Skeleton, Osseous and Cartilaginous, Mem. Amer. 
Mus. Nat. Hist., vol. i, pt. iv. October, 1899. 
T 
