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 3 T 2 o-th inches apart. In the lower jaw of the 

 skull from Honduras, the distance between the two inner 

 points of the angles is 4 I Vth 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 



