MULTITUBERCULATA. 283 
approximate size of a Rabbit. A smaller species, of which an 
upper molar tooth is represented in the figure on page 281, has 
been obtained from the Triassic rocks near Strasbourg. 
FAMILY BOLODONTID~. 
GENUS BOLODON. 
Bolodon, Owen, British Mesozoic Mamm., p. 6 (1871) ; Lydek- 
ker, Cat. Foss. Mamm. Brit. Mus., pt.v., p. 203 (1887). 
Nearly allied to the preceding family is a second one, typically 
represented by the genus 4olodon, first described from the 
upper Jurassic Purbeck rocks of Dorsetshire, but apparently 
also occurring in the corresponding beds of the United States, 
where, however, it has received a distinct name. 
In this family the four upper molars are longer than broad, 
and each carry only two longitudinal ridges, separated by a 
deep median groove, and each bearing several blunt tubercles. 
The upper premolars have triangular crowns, surmounted by 
three tubercles. 
Minute molar teeth very similar to those of Bolodon from the 
Triassic rocks of Stuttgart and Somersetshire, described by the 
name of AZzcrolestes, are perhaps referable to the present family, 
although in the absence of any knowledge as to the nature 
of the premolars, it is by no means certain that the genus 
should not rather be assigned to the undermentioned Plagiau- 
lacide. 
FAMILY POLYMASTODONTID-. 
GENUS POLYMASTODON. 
Polymastodon, Cope, American Naturalist, vol. xvi., p. 684 
(1882); Lydekker, Cat. Foss. Mamm. Brit. Mus., pt. v., 
p. 200 (1887). 
The lower Eocene rocks of New Mexico have yielded the 
