Si 
RHINOCEROS LEPTORHINUS. aid 
rhinus in the relatively thicker and more bulging base 
of the inner and anterior lobe, in the more even and 
less undulating surface, which extends from the anterior 
external to the posterior internal angle of the crown, and 
in the absence of the infundibular cavity at the posterior 
angle of the crown. 
The only portion of the vertebral column of a Rhino- 
ceros discovered at Clacton was the os sacrum ; this bone, 
by the anchylosis of five vertebra, and the broad, thick, 
rough plate of bone extending horizontally from the con- 
fluent ends of the spines of the first three vertebrae must 
have belonged, like the cranium, to a fully mature indi- 
vidual. It is of an almost equilateral triangular form, 
six inches nine lines across the base, and six inches in 
length ; it differs from the os sacrum of the Rh. Suma- 
tranus in the oblique truncation of the lower angles of 
the transverse processes of the fourth vertebra, and the 
less elongated form of the articular surfaces on the fore- 
part of those of the first vertebra. I have not had the 
opportunity of comparing this sacrum with that of the 
Rhinoceros tichorhinus ; but it most probably belongs to 
the same species as the other fossils from the fresh-water 
deposits at Clacton. 
Cuvier, having obtained evidence that a fossil humerus 
of a Rhinoceros, discovered by Professor Nesti in the Val 
d’Arno, differed from the humerus of the tichorhine Rhi- 
noceros by its longer and more slender proportions, by 
its longer and less prominent deltoid crest, and by some 
minor characters, suspected it to belong to the Rh. lepto- 
rhinus. The association with the unquestionable remains 
of that species in the fresh-water deposits at Clacton, of 
a considerable portion of a humerus of a Rhinoceros, parti- 
cipating in all the distinctive features of that from the 
