54 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
mit the vestibular branches of the acoustic nerve and the internal 
auditory artery. It may, perhaps, represent the foramen singulare 
which gives passage to the nerves for the ampullae. On the floor of 
the acoustic meatus is a small foramen which enters the cochlear por- 
tion of the periotic. If the homologies are correct this would be the 
foramen centrale and would afford passage for the cochlear branches 
of the acoustic nerve. The meatus is approximately 8 mm. deep and 
4.5mm. wide. The passage anterior to the internal acoustic meatus 
as already stated represents the internal opening of the facial canal 
or fallopian tube, which appears in the epitympanic recess as 
described above, and pierces the periotic obliquely. 
On the posterior margin of the periotic and superior to the acoustic 
meatus there is an opening which is interpreted to represent the 
external aperture for the aquaeductus vestibuli. 
LO pats 12 
Fic. 3.—INTERNAL VIEW OF RIGHT PERIOTIC OF SQUALODON CALVERTENSIS 
NEW SPECIES. X2. No. 10484, U.S.N.M.; CALVERT CLIFFS, MARYLAND. 
The dorsal surface of the anterior process of the petrosal rests 
against the petrous portion of the squamosal and the anterior margin 
is in contact with the internal pterygoid process of the alisphenoid. 
Internally, the anterior process is so intimately fused to the posterior 
process of the petrosal that they are unrecognizable as separate 
elements. 
MANDIBLE. 
The lower jaw is quite large in comparison with the size of the 
cranium and its general conformation is similar to those of other 
described squalodonts. Back of the last molar the rather delicate 
coronoid rises abruptly, and near the same point the inferior margin 
of the ramus is deflected downward; in consequence the coronoid is 
quite deep and strongly convex on the external face. Little more 
can be said concerning this portion of the mandible for the angle and 
the condyle are both missing. A long symphysis extends back to 
a point beneath the anterior margin of the alveolus for the second 
molar. The tooth-bearing portion of the lower jaw is relatively 
