100 MEMOIRS OF THE CARNEGIE MUSEUM 
teeth it bore. The teeth of the median part of the snout were more slender, but 
otherwise appear to be identical with the tooth described above. The two most 
anterior found at a point just posterior to the tip of the rostrum were small, more 
eone-like, but otherwise similar to those preserved posteriorly. It would appear 
from the evidence before me that: DBaptanodon was well provided with comparatively 
small, somewhat slender but functional teeth that extended along the full length of the 
jaw; the most anterior ones being much reduced. 
The teeth of B. discus differ from the one tooth known of B. natans in the per- 
fectly smooth enameled surface of the latter. 
Thyrohyal (th.). — Lying parallel to the posterior part of the right mandibular 
ramus of No. 878 was a subcompressed rib-like bone which T have considered the 
thyrohyal as described by Owen. There was no evidence of the corresponding bone 
of the opposite side. Both ends are expanded, more especially the posterior which 
Fia. 8. Right thyrohyal of Baptanodon discus (No. 878). One half natural size. 1, view of the inferior border ; 
2, lateral view ; a., anterior end ; p., posterior end. 
is almost twice the width of the anterior. PI. XI, fig. 1 (th.), gives the position of 
the element as retained in the matrix. 
An inspection of fig. 8 (1 and 2) shows this element as being curved from end 
to end both vertically and laterally. 
MEASUREMENTS. 
No. 878. Greatest length of thyrohyal.....: SOS OSD DaGEABCeScBNCBEcdanSabdaeABuCoooND 
“878. ‘¢ width of posterior end 
v (eirtsh “s oy anterior ‘‘ 
Tur VERTEBRAL CoLUMN. 
The material under discussion is not well adapted for a systematic study of the 
several regions of the vertebral column, and although vertebre are preserved from 
the different regions of the back bone, the vertebral series is imperfect in all of the 
skeletons in this museum. The description of this part of the axial skeleton will 
