Tertiary. | PALZZONTOLOGY OF VICTORIA. (Mammalia, 
Prate LI. 
MACROPUS TITAN (Ow.). 
[Genus MACROPUS (SHaw). (Sub-kingd. Vertebrata, Class Mammalia. Order Marsu- 
pialia. Fam. Macropodide.) 
Sea 0-0 1=1 4—4 : 
Gen. Char.—Dental formula :—7., 7 3 ¢ 993 PM Toi ™ gq = 28. Cutting 
edge of upper incisors in one line; outer one large, grooved by one or two folds of enamel 
extending from outer side obliquely forwards and inwards. The premolar displaces the 2nd and 
8rd deciduous molars, leaving d‘ and m! to m’, 
The Kangaroos or “ bilophodont” marsupials having two transverse ridges on the molar teeth 
are distinguishable as a group by that character from the Rat-Kangaroos or Bettongias, in which 
the molars are quadrituberculate. The premolar, like the anterior deciduous molar, has the crown 
lengthened antero-posteriorly, with two roots and a subtrenchant margin; the anterior and 
posterior margins in some species are thickened, and separated from the thinner middle portion 
by slight vertical side-furrows, especially in the upper jaw. 
The bilophodont molars have a “ front-lobe”’ and a “ back-lobe ;”’ a “ prebasal ridge” in 
front, and sometimes a “ postbasal ridge” behind. There are usually two longitudinal ridges, 
the “ fore-link ” uniting the prebasal ridge with the anterior lobe ; and the “ mid-link” uniting 
the two lobes ; and the “ hind-link” often descends from the hind lobe to the postbasal ridge. 
The upper molars are broader than the lower, and have a narrower prebasal ridge, but the 
“hind-link,’ from the hinder and inner angle of the hind-lobe, and the postbasal ridge, are 
larger. ] 
Description. — Upper jaw: premolar crown of two simple, conical, sub- 
compressed lobes, the hind one broader; outer surface of each lobe convex, smooth, 
divided by a vertical sulcus. It displaces d? and d*, and is smaller than d* (con- 
trasting in this respect with WZ. (S.) Atlas). It contrasts (when in place) with d4 
by being comparatively fresh and unworn. The bilophodont upper molars have a 
strong prebasal ridge, and “ fore-link” joining it to near the middle of the anterior 
lobe, inclining rather towards the inner angle. (In S. Atlas the “ fore-link” is nearly 
or quite obsolete.) ‘I'he mid-link is sinuous and tumid in the middle (being more 
strongly developed than in §. Atlas). The oblique posterior ridge is strongly 
developed, and defines a depression on the inner and under side. ‘he two lobes 
have broad convex bases in the side view (the crowns longer, in proportion to width, 
than in the S. Atlas). The hind edge of the front pier of the zygoma is in advance 
of the m?, in young, but is opposite the vertical of the middle of m?, in adults. The 
suborbital canal is nine lines in front of orbit; and three lines behind it is a small 
canal, not found in the allied living forms. The deciduous molars have four roots and 
are bilophodont, while the compressed premolar has but two roots. In the adult the 
three molars, the deciduous molar d+, and the premolar form a series of five teeth in 
a line, nearly straight on inner and slightly convex on outer edge, measuring two 
inches nine lines. In m* the prebasal ridge rises into a salient angle near the 
middle, from which the fore-link goes to the inner side of the middle of the front of 
the front-lobe; (in S. Aédas it does not rise to an angle, and there is no fore-link) ; 
the inner end bends up on the front-lobe. The mid-link comes from near the inner 
end of the fore-lobe. The postbasal ridge extends from the post-internal angle of 
od 
