1882.] MR. W. N. PARKER ON THE INDIAN TAPIR. 775 
entirely within their sockets. The last upper and lower deciduous 
molars had evidently only just come into place. 
De Blainville’ gives a description of several stages in the develop- 
ment of the Tapir’s teeth; but he is not at all clear on one or two 
important points, which I now hope to explain. 
On cutting into the jaws, distinct germs of the first and second 
premolars were seen, in the form of small conical cups, one for each 
main cusp; and of these the second in the lower jaw were the 
largest. There were no traces of the third or fourth premolars. 
It is a general rule amongst mammals that the first premolar 
has no predecessor, or else, perhaps, that this tooth is really a per- 
manent milk-tooth, the only exception usually given to this rule 
being in the case of Hyrax*. In reference to the former of these 
views, it is well known that there is a tendency in many mammals 
towards the suppression of the milk-teeth, as, for instance, in the 
Rabbit’, this being carried to an extreme in Marsupials, as Prof. 
Flower has shown’, and (as far as is yet known) in the Guinea-pig, 
in which animals the last is the only one left. On the other hand, 
as will be seen later on, the fact that in the Tapir the first milk- 
molar is considerably larger than its suecessor might be taken in 
support of the first view. It is thus interesting to find a more 
primitive condition in the dentition of animals like the Tapir and 
Hyrax. 
A comparison of the dentition of the young with that of older 
animals is instructive. As in the Horse’ and other Ungulates, the 
last deciduous molar remains functional for a long while, probably 
for some time after the animal is fullgrown; and it can be at once 
distinguished by its worn appearance. 
The first molar of the Horse appears long before the milk- 
molars are shed, and, by the time all the permanent teeth have 
appeared, is considerably worn, ‘Thus an examination of a Tapir’s 
skull in which, though apparently adult, the last milk-tooth had not 
been shed, might easily mislead one, and give the idea that there 
were only three premolars above and two below. 
That this is not the case is proved by the skull of an American 
Tapir in the Biological Museum of the Normal School of Science, 
to which Prof. Huxley has drawn my attention. In this, though 
apparently a nearly adult animal, the last milk-molars above and 
below were still functional, and above them, in the sockets, are the 
teeth which were destined to take their place. Prof. Huxley has 
also kindly allowed me to make a section of the jaw of an Indian 
1 «Ostéographie,’ tome iii. 
* Both de Blainville and Owen (Odontography, p. 605) state that in the Tapir 
the first deciduous molar is succeeded by a permanent one; but some doubt is 
thrown on this conclusion by Huxley, in his ‘Comparative Anatomy of Verte- 
brated Animals,’ p. 365. 
® See footnote on page 655 of Prof. Huxley’s article ‘On the Application of 
the Laws of Evolution to the Arrangement of the Vertebrata,” P. Z. S. 1880. 
4 Phil. Trans. 1867. 
5 Prof. Owen states (Odontography, p. 581) that in the Horse the last deci- 
duous molar is usually not shed until the last true molar has appeared. 
