EHINOCEEOS DECCANENSIS. 
7 
The lower molar series is represented by six normally-shaped tall crowned teeth — 
three premolars and three molars. Of these premolar 
The lower molar series, 2, on either side, is perfect, except that the posterior 
wall is rather broken. 
Premolar 3 is imperfect on both sides, the inner being broken away. Premolar 4 
is altogether wanting in the right ramus and wants the inner wall in the left ramus. 
Of the true molars in the right ramus, molar 1 is rather imperfect ; molar 2 and 
molar 3 are perfect in the crowns; these are figured in Plate III, figs. 2 and 3. 
It will be observed that the posterior collis of premolar 3 had only lately begun to 
come into wear. The corresponding teeth in the left ramus are less well preserved. 
The lower molars of Rh. Deccanensis are not specialized, and offer no strikingly 
characteristic differences from many other species. The guard is but sMghtly deve- 
loped on the anterior and posterior walls, and does not show on either the inner or 
outer walls in the lower molars. Molar 1 of the left side has been forced upwards 
and backwards by an intrusion of the encrusting matter, as shown in fig. 3, Plate II. 
The annexed measurements of the lower molars may be interesting for pur- 
poses of comparison — they are as exact as the imperfect state of the specimen 
admitted of their being. They were made in the following directions, after 
Mr. Boyd Dawkins’s system, at the base of the crowns : — 
1. — Antero posterior, along outside of crown. 
2. — Antero transverse, across anterior collis. 
3. - — Postero transverse, across posterior collis. 
Tooth. 
Side. 
1. 
2. 
3. 
Premolar 2 
Eight 
1" 3"' 
61'" 
Ditto 3 
Left 
1" 3'" 
Ditto 4 
do. 
1" 7'" 
Molar 1 
Eight 
1" 8"' 
i"2r 
1" 4'" 
Ditto 2 
do. 
I'll'" 
1"3" 
1" 3i" 
Ditto 3 
do. 
2" 1"' 
1"3'" 
1" 2|" 
The length of either row of lower molars on the right side is 11|- inches, 
measured along the outer bases of the crowns. 
Before passing on to the description of the much more complex upper molar 
series, it will be better to give a key to the indicative letters used in the plates, and 
which, as already mentioned, agree with those employed by Mr. Boyd Dawkins 
in his several memoirs. As both upper and lower molars are recognized to be formed 
on the same plan, though differing very greatly in the degree to which that plan was 
developed, the letters apply to the homologous parts in both series. The teeth are 
compared to a hill sub-divided by two valleys running down from the main ridge or 
outer wall of the tooth. Besides the subordinate hills thus formed, there are 
certain processes jutting from the walls of these hills into the area of the valleys, 
certain prominent ridges on the outer wall, certain remarkable ledges of 
enamel running round the sides of the walls, and certain grooves dividing the 
outer wall into areas, which all have to be accounted for, as their form, or presence, 
or absence are of great and often specific import. The comparison to a hill only 
