THE OSTEOLOGY OF HY^NODON. 505 
.pedes ^ Tl,c f„,„tcepa,-ietal suture i. ,„ite straight, end tie ..gittal crest is con. 
tnrued lertvard lor some d.stauoe upon the frontal., where it bifurcates to form the 
supraorbital ridges, dies* are best marked in H. cruc,a«: inthe other species they 
are tnconspicuous. The postorbital process is quite prominent, but leavi the orbit 
widely open be hind Anteriorly the fmutals diverge to mceivo the nasals between 
them, but usually there are no long and pointed nasal processes, though such pro- 
cesses occasionally occur in H. horridus. 
Tlie fiasals are very long, broad and transversely convex. Posteriorly they 
are wedged in between the diverging frontals, and attain their greatest breadth at 
the Ironto-niaxillary suture. The differences exhibited by these bones in the vari- 
ous species of the genus alLect chiefly the length of the portion enclosed between the 
frontals ; this is greatest in H. horridus mdi least in H . leptocephalus ; in the latter 
the broadening at the fronto-maxillary is but slight, while in H. paucidens it is very 
marked. The free end of each nasal is deeply notched and the approximated 
median projections extend over the edge of the narial opening. The mesethmoid 
is exceedingly large, even more so than in the carnivorous marsupials; its size is 
most marked in the vertical dimension, owing to the great height of the nasal 
chamber, which, however, varies in the different species, and is relatively greatest 
in //. horridus. The vomer is long and high, and the ethmo-turbinals are well 
developed and complexly folded ; the maxillo-turbinals are not displayed in any of 
the 8j)ccimens. 
T'he preniaxillaries are shaped much as in the CanidcB, and enclose a narial 
opening of similar form and relative size; the alveolar portion is thick and heavy, 
but short, the incisors forming a nearly straight transverse row. The ascending 
ramus is narrow, and does not reach the canine, which is entirely within the limits 
of the maxillary. The nasal process of the premaxillary is quite short in most of 
the species, but in H. horridus and H. crucians it is elongate and very slender, 
though, owing to the shortness of the nasal process of the frontal, the two are much 
mort“ widely separated than in Canis. The palatine processes have but a very 
limited extent, and the incisive foramina are small, hardly encroaching upon the 
maxillaries. , , , , „ .. 
The maxillaries are of great size, and make up nearly the whole of the side- 
• wulls of tlie face and nasal ch,miber; their height is greatest at the orbits and 
diiiiinislies gradually to the front. The two dental senes 
ri.,;.„risadee,con,press^^^^^^^^^^^^^^^^^^^ 
Wide interval, and seems to belong to tlit zy^, nmiscrmence of this 
an arrangement which is quite orbit and, when the jaws 
the last lower molar extends behind the bony ^ome special modifi- 
are closed, rises well above The palatine processes of the 
cation of the soft parts to provide toi t P 
