98 THE EXTINCT PECCARY OF NORTH AMERICA. 
symphysis; and indeed hardly an anatomical feature can be mentioned which does not 
present considerable variation among a large number of skulls. 
In examining the dentition, all the teeth will be found to vary considerably in size, 
though generally only in proportion with a variation in the size of the skull. The crowns 
of the first and second lower incisors indicate more or less tendency to become bilobed; 
sometimes the appearance is quite strong, at others feeble. The crowns of the upper in- 
cisors, vary in the degree of development and irregularity of their basal ridge, and in the 
degree of concavity of their interior surface. The canines vary in robustness and in the 
degree of divergence. Those below differ in the extent of development of the exterior 
ridge, which is sometimes very prominent, and occasionally is nearly obsolete. Usually 
the upper ones have an even surface, but sometimes present a longitudinal groove on 
one or both sides. As the crowns of the canines are worn down, their fangs become thick- 
ened by a deposit of cementum. 
Of the inferior molars, the last true one varies considerably in its exact form and pro- 
portions. It is oblong ovoid, trilateral, or oblong square. It sometimes presents five, nearly 
uncomplicated, mammillary tubercles; at others the unsymmetrical tubercle is more or 
less subdivided, and the crown generally presents a more complex appearance by the 
introduction of offsets from the principal tubercles ; and sometimes the fifth lobe degenerates 
into a thick basal ridge. The anterior true molars vary in the extent of corrugation of 
their lobes. The inferior premolars vary considerably in form. Their crown generally is 
ovoid, and usually presents in succession a small anterior tubercle, a transverse pair of 
large mammillary tubercles, and a broad tubercular heel. ‘The anterior tubercle is some- 
times nearly obsolete, especially in the first premolar, and occasionally in the last one. 
Not unfrequently the last premolar assumes the appearance more or less complete of a 
true molar. 
The superior molars vary in corresponding characters with the lower ones. The last 
of the series has a more or less square, or ovoidal crown, is variably corrugated, and has 
a posterior basal ridge varying in extent of development. The last premolar varies in 
form from that of the teeth preceding it to that of the succeeding true molars. The 
second premolar resembles*the one below, except that it is more square; and sometimes, it 
also assumes the appearance of a true molar. The crown of the first premolar varies in 
the degree of development of its tubercles and basal ridge. 
The value of sexual differences in the skull of Dicotyles torquatus, I have not been able 
to ascertain for want of authentic specimens of the two sexes, but perhaps the smaller 
skulls with less robust teeth, above indicated, belong to the female, while the others be- 
long to the male. 
