INDIAN TERTIARY AND POST-TERTIARY YERTEBRATA. 
SIWALIK AND NARBADA PROBOSCIDIA, 
By R. LTDEKKER, B.A., 
GEOLOGICAL SURVEY OF INDIA. 
[WITH PLATES XXIX to XLVI]. 
^Order-PROBOSCIDIA. 
Family— DINO TKFFIFFE. 
Proboscidia, in which the whole of the permanent dentition is in nse at the same 
time, and in which the second true molar has one ridge less than the preceding 
tooth. 
Dentition and aeeinities of the Dinotherida:. 
The molar dentition of Jjinotherium, the only genus of the family, in its mode 
of succession, follows the normal mammalian plan ; in the permanent dentition there 
are the full number of these teeth, while the premolars are reduced to two (penul- 
timate and last), which have succeeded more complex milk-molars. Both premolars 
are two-ridged teeth like those of the Tapir ; the penultimate milk-molar has two 
ridges, and the last three : the first true molar has three ridges, and the second and 
third have only two. In the equal number of ridges in the last milk-molar, and 
the first true molar, the genus agrees with the Mastodons, from which it is distin- 
guished by the two last true molars having a smaller, in place of a larger, number of 
ridges, than the first. 
In the one species in which the complete skull and lower jaw are known (D. 
giganteum), there are no incisors or canines in the upper jaw, but a single pair of 
large recurved incisors in the mandible. It is probable, from the form of the jaw, 
that similar incisors were developed in two Indian species, {D. indicum, D. pen- 
tapotamice), but not in a third {D. sindiense). 
In the form of its cranium JDinotherium makes a curious approach to that of 
some of the Sirenia, especially Salitherium, but has also elephantine characters. 
The last milk-molar and the first true molar are like those of the Trilophodons, 
while the other true molars are like those of Listriodon (Ungulata) : the premo- 
lars are like those of Tapirus. There is also some resemblance between the molars 
