470 



2648. A mutilated skull of a young Manatee (Manatus americanus). 



The occiput, both petro-tympano-mastoids, and the right temporal bone, are wanting. 

 The massive proportions of the zygomatic process of the remaining temporal, the curved, 

 broad, orbital process of the malar and its squamous overlapping of the corresponding part of 

 the maxillary, the sutural articulation of the orbital plate of the maxillary with the nasal 

 plate of the same bone, the fossae for the lodgement of the amygdaloid nasals, the inverted 

 arch of the palatal processes of the maxillary, the thick deflected ends of the premaxillaries, 

 and the dense texture of all the bones, are remarkable features of the present skull. The 

 glenoid cavity is rough : the large cavity in the squamosal for the lodgement of the petro- 

 tympano-mastoid is quite smooth. 



A portion of the right premaxillary bone has been removed above the shallow alveolus of 

 the small abortive incisor, which demonstrates the absence of any concealed socket of a suc- 

 cessional tooth. The deflection of the end of the upper jaw to the right is accidental, and 

 peculiar to the specimen. The molars of the American Manatee, according to Daubenton 

 and Cuvier, are 36 in number, but they are never simultaneously in place and use : their 

 crowns in the upper jaw are square, and support two transverse ridges with trituberculate 

 summits, having also an anterior and posterior basal ridge : each tooth is implanted by three 

 diverging roots, one on the inner and two on the outer side ; they increase in size very gra- 

 dually from the foremost to the last. The crowns of the anterior molars of the lower jaw 

 resemble those above, but the posterior ones have a larger posterior tubercle ; they are all 

 implanted by two fangs, which enlarge as they descend and bifurcate at the extremity. In 

 the present specimen the alveoli of the molar teeth are ^ in number, of which ^^ have 

 been fully developed and in place. 



Hunterian. 



2649. The skull of a Manatee (Manatus americanus). 



There are six teeth in place on the left side and five on the right, one having been lost in 

 front. The seventh tooth on each side is on a level with the alveolus, whilst the eighth is 

 sunk deep in its socket. There are traces of alveoli in the premaxillaries, but no teeth are 

 present. The right squamosal and petro-tympano-mastoid have been removed. 



Mus. Brit. 



2650. A right rib of a Manatee (Manatus americanus). Mus. Brit. 



2651. A right rib of a young Manatee. Hunterian. 



2652. A right rib of a large Manatee. Mus. Brit. 



2653. A rib, longitudinally bisected, of a Manatee (Manatus americanus). 



Hunterian. 



