150 
JOURNAL OF MAMMALOGY 
and has so encroached on its neighbor that it has come to occupy a median position. 
This asymmetry seems not to be found in Schizodelphis (the apparent asymmetry 
shown in Dal Piaz’s figures, 1903, pi. 1, is obviously due to distortion of the fossil). 
Although an accurate measurement is not possible, the left blowhole seems to 
have been at least 20 mm. in antero-posterior diameter, the right-hand blowhole 
about 14 mm. 
The alveoli of the upper jaw, particularly those of the right-hand side, are 
more or less slit-like, rounded posteriorly and contracted to a point forward. 
Their edges instead of being sharply defined, are rounded, with a healed-over 
appearance, and it seems probable that if teeth were present at all in the upper 
jaw they must have been very small, non-functional, and with bases buried in the 
gums instead of fitting into sockets. The posterior alveoli of the left side are 
apparently a little larger at the base of the rostrum and may have held small 
teeth. 
Most remarkable is the series of depressions seen on the palate internal to each 
tooth row, in at least the basal portion of the beak. These are obviously made 
by the tips of the mandibular teeth, and may or may not come opposite the alveoli 
of the upper jaw. Their presence indicates that the teeth of the mandible closed 
' vertically into the maxilla, that they were larger than the maxillary teeth if any 
existed, and that the width across the lower tooth rows was less than that across 
the upper alveolar series. This allowed the upper jaw to close over the lower 
jaw like the lid of a pot. A certain parallelism may be seen here with the sperm 
whale, in which the lower j aws are in like manner narrower than the width between 
the upper alveolar lines, the rostrum has at the same time become expanded, 
and the upper teeth have become functionless. No doubt this modification is a 
result of a change from an actively fish-capturing habit to one requiring less 
seizing and holding as in the squid-eating (teuthophagous) cetaceans generally. 
In the fragment, from the right side near the base of the rostrum, there are 6 
alveoli in a space of 33 mm., with intervals of from 2 to 8 or 9 mm. between them, 
and 6 depressions formed by the mandibular teeth in a space of 55 mm. In the 
larger rostral fragment (5834 Fla. Geol. Surv.) there are: 
Right side 6 alveoli in 32 mm. near base 
6 alveoli in 56 mm. near end 
6 depressions in 50 mm. about halfway 
Left side 6 alveoli in 53 mm. near base 
6 alveoli in 68 mm. about halfway 
6 depressions in 69 mm. about halfway 
In the small fragment from the tip of the beak (2343 Fla. Geol. Surv.) there appear 
to be 6 aleovli in about 35 mm. 
The posterior end of the cranium (5834 Fla. Geol. Surv.) which has served for 
the greater part of the above description, is considerably broken, but enough 
fragments remain to afford a good idea of its appearance. The condyles are large 
and prominent yet quite without the distinct neck shown in skulls of Schizodelphis 
sulcatus (Abel, 1899; Dal Piaz, 1903). That of the right side is the larger. The 
lack of a distinct neck to the cranial condyles and their large smooth surface 
tending to merge with that of the occiput show a progressive condition consider- 
ably ahead of the latter genus. The greater fore-and-aft compression is further 
shown by the notably shorter distance both relatively and absolutely between 
