58 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
VERTEBRAE. 
Five vertebrae were found associated with the skull and mandible. 
Of these two are ‘dorsals, the others lumbars; all of the vertebrae 
lack epiphyses. Six epiphyses (pl. 13, figs. 3-4; pl. 14, figs. 1-2; pl. 15, 
figs. 1-2) were found embedded in the matrix. The vertebrae are 
very soft and porous, and were with difficulty extracted from the 
matrix. 
The dorsals differ noticeably from those of Delphinodon and to a 
less extent from those of Eurhinodelphis. A comparison of these 
vertebrae with the dorsal series of Inia geoffrensis shows that one 
(pl. 9, figs. 1-3) unquestionably represents one of the more anterior 
dorsals; the other belongs near the end of the series. The structural 
peculiarities and the general appearance of the anterior dorsal suggest 
the second dorsal. If this determination is correct, then certain pe- 
culiar features are accentuated. Using the length of the centrum as 
a basis for allocation, this vertebra would be placed fourth or fifth in 
the dorsal series. However, the position of the articular facet for the 
head of the rib and the small size of the anterior facets for the post- 
zygapophyses of the preceding vertebra would place the vertebra 
anterior to the fourth dorsal. 
It differs from an anterior dorsal of Hurhinodelphis in having a 
longer neural spine, a relatively larger neural canal, lighter neural 
arches, and in the possession of a deep groove on the lower half of 
the posterior face of the neural spine. The anterior dorsals of Inia 
geoffrensis also possess neural spines with similar grooves. 
The centrum, including the epiphyses, was nearly as thick as broad. 
The neural canal is large and rounded, almost as large as the centrum. 
The zygapophyses are not developed as distinct processes, but are 
limited to articular surfaces for the corresponding processes of the 
adjoining vertebrae. The anterior facets are situated on the internal 
margins of the neurapophyses and the posterior on the ventral faces 
of the same arches. 
The transverse processes or diapophyses are short and blunt, di- 
rected outward and slightly forward. The neural spine is broken 
superiorly. 
The other dorsal vertebra (pl. 10, figs. 1-3) to be discussed occupied 
a more posterior position in the series than the preceding. ‘The trans- 
verse processes are shortened and are so situated that their long axes 
are in a line with the top of the centrum. Each process bears a facet 
for the head of arib. In Jnia geoffrensis the’ facet for the head of the 
rib shifts from the anterior margin of the neural arch on the first 
dorsal to the top of the centrum on the eleventh dorsal. This feature 
occurs also in other cetaceans, and if any reliance can be placed on 
it then this vertebra is the eleventh in the dorsal series. The twelfth 
dorsal of nia bears a facet on the tip of the flattened transverse proc- 
