282 PROBOSCIDIA. 
the old Mastoden, the summits of all the mastoid emi- 
nences having been abraded by mastication ; but they are 
not so much worn as in a naturally shed tooth. There 
are eight principal tubercles, with a small anterior basal 
ridge, and a larger posterior talon. The intermediate 
connecting eminences in the first and second valleys are 
worn down to their basal confluence with the larger 
mastoid tubercles, and thereby occasion a more complete 
alternate arrangement of these principal divisions of the 
crown. The wavy fibrous texture of the enamel is re- 
markably well shown in the fractured surfaces of the very 
thick layer of that substance which invests the crown. 
The dentine is reduced to a very brittle friable condition, 
and the fangs are entirely broken away. 
Two views of a large portion of a corresponding tooth 
of the A/astodon angustidens are given by Mr. Samuel 
Woodward ina Paper ‘On Remains of Mastodon gigan- 
teus and Mastodon latidens, found in the Tertiary Beds 
of Norfolk.* I have examined the casts of the original 
specimen figured, which are now in the Geological Society’s 
Museum, and can affirm that this tooth belonged neither 
to the American nor to the Indian species of Mastodon, 
cited by Mr. Woodward, but to the Mastodon angustidens. 
Mr. Layton thus recounts some of the circumstances at- 
tending the discovery of the molar tooth figured by Mr. 
Woodward, in a communication printed by Mr. Fair- 
holme, in his ‘ Geology of Scripture,’ p. 281 :— 
“In 1820, an entire skeleton of the great Mastodon 
was found at Horstead, near Norwich, lying on its side, 
stretched out between the chalk and the gravel. A grinder 
was brought to me ; but, so long after it was discovered, that 
scarcely any other part of the animal could be preserved.” 
* © Loudon’s Magazine of Natural History,’ vol. ix. (1836,) p. 131. 
