302 PROFESSOR OWEN ON SOME SPECIES OF THE EXTINCT GENUS NESOUON. 
The third incisor {i 3) has the anterior surface turned more outwards, but similarly 
subequally divided into two facets, the mesial one lying- directly behind and upon 
the second incisor ; the posterior surface is more flattened ; the inner border is sharper 
and more produced ; the outer angle of the crown is rounded ofl". The length of the 
crown is 10 lines, its greatest breadth, which is below the worn end, is 7|- lines ; the 
fang is somewhat shorter and thicker, but contracts, like the others, to its end; its 
length is 11 lines, fig. 12. 
The canine (e) rises and slopes forwards close behind the third incisor ; it is of 
smaller size, with the fore-part of the crown more convex, and unequally divided 
by a longitudinal eminence nearer its outer border ; the posterior surface is con- 
cave ; the summit is thin, rounded, with the enamel not worn off, although it is 
on the same level with those of the incisors. The crown is 9 lines long and 6 lines 
broad, half-way down. The enamel is continued much further down the fore than 
the back part of the crown in the incisors and canines, and the length of the crown 
has been taken from the fore-part. The fang of the canine (c, fig. 12) is 7 lines in 
length. 
The first premolar (p i) rises behind and to the inner side of the canine; the two 
surfaces of the crown are directed outwards and inwards ; the outer surface has its 
anterior half convex, its posterior half concave ; the convex part rests on the concave 
surface of the canine, and the concave part receives the lower part of the anterior 
convexity of the second premolar. The working border rises to an obtuse point 
formed by the summit of the longitudinal prominence dividing the two parts of the 
outer surface. The inner surface is slightly concave anteriorly. The height or 
length of the crown is 9 lines, the breadth of the crown is 8 lines. It is implanted by 
a single, short and thick, moderately tapering, and obtusely ended fang, 6 lines in 
length (p 1 , fig. 12). 
The second premolar (p 2) has the crown divided into two equal lobes by a wide 
and deep longitudinal angular indentation on its outer surface. The anterior lobe is 
the most prominent one, and has three sides, the antero- external surface being trans- 
versely convex : the postero-external one flat, and the internal surface concave. The 
inner concavity of the hinder lobe sinks at its lower end into the substance of that 
lobe. The whole crown is convex vertically on the outside, concave on the inside, 
being slightly bent inwards in the direction of its length ; this measures 10 lines, the 
breadth is 8 lines; the crown gradually contracts to the fangs (jw 2, fig. 12), which 
are two in number, and diverge as they penetrate the sockets; their transverse 
breadth is considerable ; their length 6 lines. The anterior one passes external to the 
fang of the first premolar, which is wedged, as it were, into the internal interspace 
between the canine and the second premolar. 
The third premolar {ps, figs. 12 and 14) presents the general complex form and 
structure characteristic of the true molars. The external entering angle marks oft" 
the anterior third of the crown as the anterior lobe, which is convex transversely. 
