THE CHIMPANZEES AND ORANGS. 169 
which, as shown in the Table of Admeasurements (p. 175), these teeth are so much 
smaller,—the normal series of five not exceeding in fore-and-aft extent that of the last 
four of the same series in the other skull,—the smallness of the normal series has been 
compensated by the superaddition of a fourth molar on each side of the upper jaw, 
which makes the series of equal extent with that of the other skull. This supernumerary 
tooth is smaller than the last; it had not emerged from its formative cavity on the left 
side, nor attained the level of the grinding surface on the right side. There is no trace 
of a corresponding supernumerary tooth of the lower jaw of the same individual, in 
which the extent of the normal series of five grinders equals that of the six teeth above. 
The extent of the grinding surface of the molar series in the other male Morio (no. 2) 
exceeds that in the above-described, owing to the larger size of the crowns of the teeth, 
which are of the usual kind and number. 
In one of the skulls of the female Pzthecus Morio, transmitted by Mr. Wallace, the left 
series of molars in the lower jaw shows a supernumerary or fourth true molar ; it is rather 
more than half the size of the contiguous m3, which is not less than the m3 of the 
right side, where there is no trace of the sixth tooth or its socket. That tooth on the 
left side has its crown in a proper position for use, and the fore and outer angle has 
been worn by the action of the last molar, m3, above. There is no trace of the super- 
numerary tooth on either side of the upper jaw. The length of the molar series here is 
1 inch 114 lines; of the right side, lower jaw, 2 inches 3 lines; of the left side, lower 
jaw, 2 inches 6 lines. 
I first noticed the variety of the supernumerary molar tooth in a skeleton of an adult 
male Orang (P. Satyrus) in the collection of Baron Van der Capella (formerly Governor 
of Batavia) at Utrecht’, in the year 1838. In an adult of the large Bornean Orang, 
which Mr. Blyth believed to be a female, in the Calcutta Museum, but which from the 
size of the canines I deem to be a male, he records a similar anomaly, in ‘‘a fourth 
true molar, above and below, though on the left side only ; that of the upper jaw being 
of small size and round form, its crown scarcely exceeding that of an upper false molar 
of Macacus rhesus; in the lower jaw the accessory fourth true molar is very little 
smaller than the normal molars; its crown is directed obliquely inwards, so that as a 
functional tooth it must have been almost useless; but the outer or upper margin of 
its crown is a little worn by attrition, as is also the outer cusp of the small accessory 
molar above.” 
In consequence of the superior size of the upper incisors and canines in the male 
Morio, no. 1, there is no vacant space between the outer incisor and canine in that 
skull, and the series of teeth is as continuous in both jaws as it is in the Human 
subject (Pls. XXXI. & XLVIII.): the points of the long canines are so directed as to 
overlap, when the mouth is shut, the intervals of those teeth, which are widened into 
1 Odontography, p. 442. 
2 Blyth, “ Further remarks on the different species of Orang,” Joc. cit. p, 3. 
