634 
ME. W. H. FLOWEE ON THE DEVELOPMENT AND 
didoe agree in all essentials with those of the type, differing only in the form of the 
crowns of the molars and premolars and the longer or shorter persistence of the rudi- 
mental maxillary canine, we may conclude that their development follows the same rule, 
and such observations as I have been able to make fully bear out this conclusion. Dif- 
ferences, however, occur in the order of the evolution of the teeth among themselves. 
Thus in Hypsiprymnus, the reserve premolar is relatively later in acquiring its position 
in the jaw than in Macropus , being still in germ, at least in some species (see Plate XXIX. 
fig. 4), after the last permanent molar is in place and use. This probably has relation 
to the extraordinary size of this tooth, and the length of time consequently required for 
its development. Moreover this tooth, as well as the anterior true molars, are not com- 
monly lost during the lifetime of the animal as in the great Kangaroo. 
Family Phalangistidjb. 
Phalangista vulpina. 
1 . A marsupial foetus, nearly destitute of hair. Entire length 8 inches, of which the 
head occupied 1*7, and the tail 3*5. Eyelids open. Lateral margins of the lips not ad- 
herent (see Plate XXIX. fig. 5). 
There were no teeth above the gums in either jaw ; but the prominent apices of the 
first and second upper incisors, the lower incisors, and the two anterior teeth of the molar 
series raised the overlying mucous membrane. 
On dissection, the crowns of the three upper incisors were found to be calcified, and 
corresponding in form and size to those of the adult animal. The conical crown of the 
canine was calcified, but lay deep in the alveolus. The large temporary molar (coloured 
red) and the first and second true molars had also solid crowns. Above the former was a 
slightly calcified germ of the reserve premolar (coloured blue). The capsule of the third 
true molar was distinct. In the lower jaw, the large procumbent incisor was half an 
inch in length. An extremely minute canine, with its apex calcified, lay close to the 
alveolar border ; the molar series resembled those of the maxilla in their development, 
but the germ of the reserve premolar was still a soft papilla. 
2. An older specimen, well covered with hair, measured from the nose to the end of the 
tail 13*5 inches, of which the head occupied 2*1 and the tail 6. In the upper jaw (Plate 
XXIX. fig. 6), the apices of the first and second incisors protruded through the gum ; as 
did the cusps of two molar teeth (the temporary and the first permanent molar). In the 
mandible, the broad, flat, cutting extremity of the incisor projected about xg- inch beyond 
the membrane ; the rudimentary canine was also seen, and the cusps of two molars 
as in the maxilla. 
On dissection the appearances found resembled those described in the last specimen ; 
but all the teeth were in a more advanced condition of development. The crowns of 
both reserve premolars and of the third true molar were largely calcified. No trace of 
the fourth true molar could be detected. Between the canine and the temporary molar 
was a small conical germ of one of the rudimental premolars. 
