OSTEOLOGY AND DENTITION OF HYLOMYS. 459 
approaches more to that of Hrinaceus, which it also resembles in its stouter horizontal 
ramus, and in the more erect position and form of.its coronoid. The condylar articular 
surface has not a great transverse extension. ‘The ridge (internal) running from the con- 
dyle to the ramus is very prominent. ‘The anterior orifice of the dental canal is below the 
anterior margin of the last premolar. The process of the angle is hook-like and pointed. 
The dental formula is :—i. sty ct ith pm. th m. gig 44 (figs. 5, 6, & 7). 
The first incisor is conical and curved, with a very minute posterior cusp at the base 
of the crown. ‘The second incisor, separated by a short interval from the first, is con- 
siderably smaller than that tooth, and is not so much curved; but it has also a minute 
cusp at its base posteriorly. It has about the same length as the canine. The third 
incisor is placed close to the second, and is about half its size, but differs from it 
in having a small, laterally compressed, almost triangular crown, with a constriction 
above it, the posterior basal angle of the crown showing the indication of a rudi- 
mentary cusp. The canine is immediately behind the premaxillary suture, separated 
by a short interval from the third incisor. The anterior half of its crown resembles the 
second incisor; but the hinder half bears a minute, almost hook-shaped cusp at its base. 
The first premolar is immediately behind the canine, and is followed in close succession 
by the second and third premolars, all having the cingulum more or less developed 
internally and externally. They are all small teeth, with about the same downward 
extension. The second is slightly larger than the tooth on either side of it; but 
all are of about the same length as the third incisor. Each has a central conical 
crown, very faintly curved, with a small cusp at its base anteriorly and posteriorly, a 
development of the cingulum. The anterior cusp is most developed in the second ; and 
the third tooth has the most pronouncedly marked posterior cusp, with the anterior 
cusp hardly visible. The crown of this last-mentioned tooth is more truncated than 
that of the others. These premolars have a much stronger resemblance to the first, 
small anterior premolars of Hrinaceus than to the corresponding teeth of Tupaia. The 
fourth premolar is a large tricuspidate tooth, with an external cingulum and large 
pointedly conical crown, which has the greatest vertical extension of all the teeth in 
the upper jaw. It has two internal, pointed, conical cusps, the anterior of which is 
much the longer and larger. Besides these, however, the cingulum is so much 
developed posterior to the crown that it almost produces another cusp. This tooth is 
very closely allied by its structure to the last premolar of Erinaceus, and is very dif- 
ferent from the same tooth of Tupaia. It is almost the exact fellow of the former. 
The fourth molar is the largest of the teeth in the upper jaw, and consists of four 
cusps, two external and two internal; but the cingulum which encircles the tooth is 
very strongly developed externally, and behind the postero-external cusps it almost 
forms a fifth cusp. The anterior of the external cusps, which are conical with a 
greater vertical extent than the internal cusps, has a less vertical extent than its fellow. 
The internal cusps are the same as in Hrinaceus. Situated, internal to the postero- 
