294 PROFESSOR OWEN ON SOME SPECIES OF THE EXTINCT GENUS NESODON. 
diminish from the first (innermost) to the third, and vary more in form than size. The 
first (figs. 1 and 4, i i) is curved, with the convexity foremost ; the fang is slender 
and contracts as it penetrates the bone; the crown expands and presents the true 
trenchant incisive form, is flattened transversely at the fore-part, and slightly convex 
at the back, with the edge worn flat, but with a slightly raised thin enamel ridp 
The second incisor (ib. i 2 ) does not quite touch the first ; its crown is curve , ^t 
the most prominent convexity at its fore-part, but it is nariowei than in the , 
and is three-sided, the outer and hinder facets being broader than the front one. 
The enamel is not continued upon the hinder facet: the contracted fang shows it 
to be, like the first incisor, a tooth of restricted growth. It is inserted at the ang e 
of the premaxillary, where the front wall bends to form the side wall, and is externa 
and a little posterior to the first incisor. The third incisor (ib. is) is double its 
own breadth’s distance from the second, and is implanted behind it, close to the 
suture with the maxillary; the crown is short, subtrihedral, and so much smaller 
than the others, as almost to be termed rudimental ; it is, however, worn obliquely, 
like the crown of the second incisor. 
The canine (figs. 1, c and 3, c) is intermediate in size between the third and secon 
incisors; it is implanted near the suture: the summit of its crown, which was 
conical and subcorapressed, is worn away ; its outer side presents a middle convexity 
bounded by a narrow longitudinal channel near each margin. ^ . 1 • 
The first grinder (ib. d i) is about the size of the second incisor, and is I 2 hne 
distant from the canine ; its crown is thicker as well as broader and longer than that 
of the canine ; the external convexity is produced into a longitudinal ridge near t e 
fore-part of the crown, and its summit forms the most prominent part of the giin ing 
surface, which surface slopes away both forwards and backwards from it, the hinder 
worn facet being much the largest. The base of the crown contracts and divides into 
two short nearly parallel fangs. The entire length of the tooth is 7 lines. 
The second grinder (ib. d 2), of nearly twice the size of the first, close behin w 11 c 1 
it is placed, presents two longitudinal ridges dividing three grooves on its outer 
surface, and a triradiate termination of an inflected fold of enamel at the midd e 0 
the grinding surface. The length (vertical diameter) of the crown is 5 lines, and it is 
implanted by short diverging fangs, two of which are external, and aie expose m 
Plate XVI. fig. b,d^-, the total length of this tooth is 7\ lines. 
The third grinder {d., figs. 1, 3, 5) presents somewhat more than a proportional 
increase over the second, the hind fourth of which it overlaps, its breadth being 
6^ lines. The anterior of the two longitudinal eminences on the outer side of the 
crown is more prominent and angular than the second convexity which has begun 
to expand and subside, and the anterior overlapping border of the crown is com- 
pressed and produced like a ridge. A fold of enamel penetrates the middle of the 
inner side of the crown, dips into its substance, contracts as it proceeds outwards 
and forwards, and bifurcates ; behind this there is a small pit or island of ename : 
