30 MR. A. L. ADAMS ON THE OSTEOLOGY OF 
remainder of the ridges (nine) are contained in a space of 4:2 inches; so that by making 
the same allowance for the lost portion as in the cases of the Zebbug molar and 
No. 281, there would have been fourteen ridges in about 53 inches, 7. e. supposing the 
teeth to have been last true molars. At all events it is clear that their ridge-formulas 
eaceeded ten plates and two talons. ‘This is further shown by the following, which re- 
presents the palatal region containing a fragment of the left and almost the entire right 
molar im situ. 
3. The specimen in the B. M. (No. 87) has been much injured, and the posterior talon 
has been recently lost. The crown is not nearly sofar advanced in wearas the last, the four 
posterior ridges being intact. There is a small field of dentine in front, 0°5 inch, and 
sufficient to have maintained an extra ridge. As the tooth stands, there are thirteen 
ridges in 5:5 inches; and from its state of wear it may be said to be entire, with the 
exception of the loss of the last ridge. In crown-constituents it repeats precisely the 
characters of the preceding, and from its long graduating crown indicates at all events 
the usual contours of the penultimate and last upper true molars. ‘The crown-pattern in 
Pl. IV. fig 1 and No. 87 are precisely alike, and also correspond with the two pre- 
ceding. Now, in comparison with No. 28 and the Zebbug molar, it will be found that 
the two just described contain an extra ridge in a given space; thus the two former 
hold seven ridges in the same space occupied by six ridges in the two latter. 
4, One of the most characteristic and instructive specimens in my collection is the 
portion of a right lower ramus, No. 95 (Pl. VI. fig. 1), containing an entire molar 
(fig. 1a) which has been detached and is represented of the natural size in order to 
show its outline. Here we have the character not rare in last true molars of recent and 
fossil species when the posterior ridges become reclinate, so that the posterior talon ¢ 
(fig. 1a) is nearly horizontal. The tooth in this instance fills the ramus, so that its base 
posteriorly reaches to 4 (fig. 1), or in other words, within a short distance of the opening 
of the dental foramen. ‘There is an indication of the bony alveolar septum behind ; so 
that, to all appearance, the only conclusion we can come to is that the molar is the 
last of the dental series. It contains fourteen ridges in about 6 inches. Excepting 
the ten disks in wear, the remainder of the collines are more or less hidden by the 
investing cement; but their tips are determinable. 
It will be seen from fig. 1a that the ridges are crowded, and that the enamel is 
decidedly thin as compared with the upper teeth; there is faint crimping, however, with 
central expansions and angulations on the well-worn disks. It may be here observed 
that the surface in wear represents the entire attrition-plane, as no fragment of a pre- 
ceding molar is noticeable. From this circumstance, therefore, and the space occupied 
by the tooth, it seems to me to afford conclusive proof of its being a last true molar of 
a very small species of elephant. 
’ I have invariably estimated the average width of the ridges by measurements taken at the base of the crown, 
so as to overcome the errors likely to arise from measuring disks in various stages of wear. 
