ON thp: structure and classification 
the lamest- it continues the line of the lower border of the jaw; the crown broadens 
towards the tin and is flattened upon the upper surface. The series dimimshes m 
size towards the canine, while the inter-spaces increase, and, judging by the fang^ 
which is all that remains of this tooth was diminutive. The canine has a high, 
strongly procumbent crown; its fang is slightly grooved (No. 47,767), and in another 
specimen (No. 47 , 768 ) there are two distinct fangs. There are four bifanged premolars, 
which increase rapidly in size posteriorly; are broken; pm^ has a high, re- 
curved crown with a simple convex anterior slope, and a low posterior heel ; pm 4 has 
a slightly stouter crown, and a broad posterior heel. The apparently single-fanged, 
styloid molars suggested to Professor Owen the appropriate name of the genus ; there 
are seven distinct molars, with the indications of an eighth, in one specimen, (Mes. 
Mamm., p. 52, PI. II, fig- 18a). 
External aspect of the molars. The first molar is low and obtuse, with a broad 
ba.se, and is distinguished from the premolars principally by its single fang; the cin- 
gulum rises anteriorly into a faint basal cusp. The second molar has a broad fang 
and rather stout conical crown, with a distinct cingulum ; is nearer the typical 
molar pattern, the cingidum rising anteriorly; 4 is a typical styloid molar, with a 
rather narrow base, distinct cingulum and lofty tapering crown; and are 
.slightly smaller, while m-, is a much smaller tooth. 
In another sjjecimen, "(No. 47 , 758 ), the molars are still more slender and tapering. 
Unfortunately none of the specimens present the inner surface of the ramus, but 
much additional knowledge of the molars is derived from jaws in which the teeth are 
partially rotated in their sockets. Thus in PI. II, fig. 18a, Mes. Mamm., we see that 
the crown is not actually styloid but rather chisel-shaped, with its greatest diameter 
tninsver.se and the wearing surface sloping obliquely inwards and downwards from the 
outer tij). In fig. It), PI. II, an internal cusp upon is represented, and in fig. 15a, 
the molars arc more compactly placed, and has an internal heel. In PI. Ill, fig. 2, 
»«#, the molar is nearly in side view, and shows what may represent part of an inner 
fang. 1 his accords with the conjecture of the writer, that these molars are not single- 
fanged, but have two fangs placed transversely, as in the upper molars of Kurtodon. 
Since the above was written Professor Marsh has discovered the full pattern of 
the Stylodon type of molar, viz, a styloid external and tricuspid internal face, 
which renders it probable that some of the specimens attributed to Amhlotlierium and 
other genera, present the internal mandibular aspect of Stylodon, or an allied genus. 
KURTODON, KQen. iVoiO^ Plate IX. Fig. 15. 
I he type of this genus is the single maxilla (No. 47,755) tvhich was referred by 
Professor Owen to Stylodon (Mes. Mamm. p. 48. PI. II, fig. 14.) 
• The name Athrodon Was at first assigned to this 
preoccupied by Sauvage (Bull. Soc. Geol. 1880, p. 630). 
genus (Proc. Phila. Acad. June, 1887), but is found to be 
Kurtodon was substituted later, (Am. Nat., Nov., 1887.) 
