544 The American Naturaist. [June 
margin. It is vertical in position, and the smooth posterior sur- 
face is ornamented with semi-circular rows of foramina and fissures. 
“which give insertion to the short, tough fibres by which the 
dermal coat is bound to the shield throughout.” According to 
the dissection of Mr. Atkinson, the sphceroma is completely 
invested on doth its surfaces by the common integument of the 
body, so that the anterior concavity and the bony fulcra inplanted 
into it are clothed with hairy skin, reflected from the back, 
while the posterior surface is covered by the closely adherent 
continuation of the dermal horny coat. The caudal vertebrae are 
fourteen in number ; the transverse processes of the eighth, ninth, 
tenth, and eleventh are elongated so as to produce a spatulate 
condition of the organ. 
The cranium is conical, capacious, compressed, and without - 
sutures. Seen in profile, owing to the elevation of the vertex, as 
well as to the concavity between the two singular rounded pro- — 
cesses which are given off from the frontal and which connect 
with the olfactory organs, the contour of the cranium reminds 
one of the Indian elephant. Especially is the mandible ungulate 
in its character, in its depth, perpendicular ramus, rounded angle, 
and in the condyloid process being longer than the coronoid. 
From the anterior portion of the two frontal tuberosities a narrow 
ridge on either side converges towards the nose. The elongate 
nasal bones terminate at an orifice, opening downward. 
The dental system is composed of eight molars on either side 
of both jaws. The teeth are long, cylindrical, have no true roots 
or crowns, are encircled by enamel, are so deeply set that those. 
of the mandible dimple its inferior margin. They are slightly 
curved. The orbital and temporal fosse are not separated. The 
zygomatic arch is slender posteriorly, but anteriorly it is mor 
developed with a descending process from the malar. 
The external meatus auditorius is prolonged in the form of a 
long, winding, cylindrical osseous tube, ascending behind the — 
articulation of the jaws, and, arching over the roof of the zygoma 
terminates in an aperture just behind the éye. This osseous tube 
is composed of two separate pieces, which are joined by an inter- 
posed ring of cartilage. This very remarkable auditory app% 
