The Skull of the Manatus Senegalensis and Manatee. 265 
ronoid process is nearly 4 inches, the upper border of the 
coronoid process rising two-thirds of an inch higher than the 
condyle. The maxillary canal greatly exceeds in size that in 
the African skull, and is not separated from the inflated 
extremity of the alveolar process posteriorly. It terminates 
in front in a wide-grooved foramen menti, with another fora- 
men behind, which communicates with the maxillary canal, 
and is equal in size to the true foramen menti in the African 
skull. The distance from the angle of the lower jaw to the 
symphysis menti is about 4 inches, and the angle of the jaw 
is but slightly inflected, whilst in the African skull there is 
an acute inflected angle, the two inner points of the angles 
being only Sy^th inches apart. In the lower jaw of the 
skull from Honduras, the distance between the two inner 
points of the angles is 4i\th inches. 
The alveolar process of the lower jaw is 5 inches in length, 
slightly curved outwards and upwards at the posterior ter- 
mination, where it perforates the roof of the coronoid pro- 
cess, and protrudes by its inflated extremity into the maxil- 
lary foramen. 
There are eight molar teeth on the left side of the lower 
jaw, and an empty socket in front ; each tooth has two large 
transverse bi-tuberculated ridges, and a smaller ridge be- 
hind, implanted by two roots in sockets about an inch deep, 
like those in the lower jaw of the African skull. The roots 
of the teeth are flattened transversely, corresponding to the 
transverse coronal ridges, and the posterior root is bifurcate 
at the apex. 
The molar teeth in the upper jaw have two transverse tri- 
tuberculated ridges, with a ridge-like thickening at the 
cervix anteriorly and posteriorly, similar to, but less in size 
than those in the African skull. Each molar tooth in the 
upper jaw has three roots, the inner root compressed longi- 
tudinally, the two outer roots compressed transversely ; but 
the roots of the teeth are less divergent, and the external 
anterior root is less curved backwards, than those in the 
African skull. The three posterior teeth on each side of each 
jaw are nidamental ; the three succeeding teeth are but very 
slightly worn ; whilst those in front, still in situ, have their 
