Chlamyphorus truncatus. 159 



The labyrinth is protuberant and occupies the usual situation 

 at the base of the skull : joined to which is the tympanum ;— to 

 the last is attached a bony cylinder stretching first upwards be- 

 hind the zygomatic process of the temporal bone, around which 

 it makes a sudden curve, and runs forward and upwards to ter- 

 minate at the external ear. 



Lower jaw. Anterior portion shaped like that of the elephant, 

 much elongated ; the general form and proportion resembles very 

 closely the lower jaw of the sheep, the base being considerably 

 arched, and the curve at the posterior part, forming with the base 

 nearly a right angle, projecting obliquely outwards ; the base is 

 marked by eight slightly elevated protuberances, occasioned by 

 the roots of the teeth ; the condyloid process is longer than the 

 coronoid ; in the sheep this is reversed : the articulation at the 

 glenoid cavity as such as to admit of great freedom of motion. 

 Length of the base of the lower jaw one inch ; length of the 

 angle five-tenths; greatest width two and a half tenths; width 

 of the angle three-tenths. 



Teeth. Incisors, none in either jaw; molars, eight in number, 

 on either side of the upper r.nd lower jaws, all approximate; dis- 

 posed in separate alveoli ; the crowns of the tM'o first only, ap- 

 proach to a point, and thus much resemble canine teeth ; the six 

 remaining are all nearly flat on the crowns ; their structure is 

 simple ; a cylinder of enamel, of equal thickness throughout, 

 surrounds a central pillar of bone ; there being no division into 

 body and root ; the lower half is hollow, the cavity representing 

 an elongated cone. In the lower jaw, the teeth penetrate its 

 whole depth ; — length of the teeth, about three-tenths of an 

 inch: two-tenths of which are buried in the sockets — diameter, 

 about one-tenth. They are somewhat flattened on the sides, and 

 in a slight degree curved externally, to be adapted to the shape of 

 the jaw. The teeth of the inferior maxilla are directed forwards 

 and upwards ; those of the superior maxilla are directly reversed 

 in their direction, so that the crowns meet each other obliquely ; 

 and the posterior margin of the lower teeth, and the anterior mar- 

 gin of the upper, present their angles to the object of mastication. 

 The remainder of the skeleton, with the viscera, having been 



