BRITNIQUEL, AND ITS ORGANIC CONTENTS. 
541 
the posterior prong extends backward along the anterior third of the grinding- surface. 
The mid internal fold, f, is deeper than in Hipparion. The postinternal fold, g, penetrates 
one-third the thickness of the crown, then extends pretty equally forward and backward, 
like the cross of the capital T ; the forward production is longest in the two anterior, 
p 2, p 3, and shortest in the two posterior grinders, m 2, m 3. The hind lobule, l , 
decreases in transverse and increases in fore-and-aft extent from the second to the sixth 
grinders, in which it rather suddenly attains its maximum. 
The above particulars are, in the main, rather generic than specific characters of the 
existing equine lower grinders ; but the definition is requisite for carrying out subsequent 
comparisons, in which the specific marks of the molars of Eq. caballus will be made more 
apparent. 
Equus asinus. — The subjects of Plate LYIII. figs. 1 & 2 are from a male Ass of 
the ordinary English domestic race and average size, about eight years old. In the 
upper series of grinders (fig. 1) the degree of oblique attrition of p 2 occasions the 
appearance of the working-surface of that tooth being more produced and acute ante- 
riorly than it is in less worn and more evenly worn specimens. Besides the general 
inferiority of size of the teeth, that of m 3 is relatively less than in E. caballus, and it is 
not bilobed behind; the outer longitudinal channels, f, f, are more evenly curved or 
concave ; and, as the same character prevails in the inner enamel-wall of the lobes a, b, 
these are more regularly crescentic in shape. The longitudinal ridge, n, is relatively 
narrower ; the posterior boundary of the channel, f, is not produced in m 2 and m 3, and 
but feebly so in m 1. The lobule, m , has less antero-posterior extent than in the Horse. 
In the molars of a she-ass I find the inner margin of this lobe feebly indented near the 
middle*. A slight excess of fore-and-aft over transverse diameter of grinding-surface is 
recognizable in the Ass — such excess not being seen in the permanent grinders, p 3 -m 2, 
of the Horse. The length of the upper molar series is 5 inches 10^ lines in the male, 
and 6 inches in one of the female Asses here examined : in the latter the interval 
between the right and left molars, m 3, is 2 inches 6 lines ; between the right and left 
premolars, p 2, 1 inch 9 lines. The premolars form a greater share of the length of the 
grinding series than in the Horse. 
In the lower molar series the relative inferiority of size of m 3, as compared with 
E. caballus , is also seen ; and, as in the upper series, the three premolars occupy a larger 
extent of jaw compared with the three molars, than they do in Eq. caballus. The ante- 
rior fork of the fold k is more extended transversely toward the outer side of the crown. 
Equus hemionus. — The subjects of Plate LYIII. figs. 3 & 4 are from a male Kiang (Eq. 
hemionus , Pallas 1), from a skull ascribed to that species in Gray and Gerrard’s ‘ Cata- 
logue of the Bones of Mammalia in the Collection of the British Museum,’ 8vo, 1862, 
p. 274. The skull is marked ‘ 976, h', and was transmitted from Nepal by B. H. Hodgson. 
Esq., H.E.I.C.’s Resident in that Province. It may have been received from Tibet. It 
* I am indebted to Professor Wortley Axe, of the Royal Veterinary College, for the opportunity of comparing 
specimens of the Ass’s dentition with those in the British Museum. 
4 D 
MDCCCLXIX. 
