440 Prof. E. D. Cope—On the Proboscidea. 
The characters assigned to the above genera are sufficient to 
separate them, but they have not come into general use for two 
reasons. One is the difficulty of verifying some of them, especially 
the presence of premolars, owing to the difficulty of obtaining 
specimens of young individuals. The other is the indisposition of 
naturalists to abandon the system of Falconer. As is well known, 
this able paleeontologist distinguished the genera by the number and 
depth of the transverse crests of the molar teeth, and the extent to 
which their interspaces are filled with cementum. This arrangement 
is insufficient, since it neglects the equally important characters 
above mentioned ; and as observed by Lydekker? it fails to furnish 
clear definitions. He remarks, under the head of the genus Elephas :— 
“There is no character by which the present genus can be dis- 
tinguished from Mastodon; and the division can be therefore only 
regarded as a matter of convenience.” The characters presented in 
the above table are on the other hand very distinctive, and can be 
applied in all cases where we have the necessary information. This 
has not yet been obtained as regards all the species, and I have 
placed some of them in their respective genera provisionally. Such 
species are marked with an 7, when the condition of the incisors is 
unknown and with a p, when the same is true of the premolars. 
The species of the family described thus far are as follows: ?— 
Mastodon (Tetrabelodon) brevidens,® Cope, sp. nov.. N. America, i.p. 
vs . turicensis, Schinz. Kurope. 
+3 rp angustidens, Cuy. , Kurope. 
Ae Dein - paleindicus, Lyd. India. 
Ap a A proevus, Cope, N. America. 
6 a productus, Cope. N. America, ? Mexico. 
ie is . euhypodon, Cope. N. America, p. 
or A pandionis, Falc. Cautl. . India. 
is re pentelict, Gaudry.* Europe, p. 
Ge a3 campester, Cope. N. America, p. 
an a longirostris, Kaup. Europe. 
HS P serridens, Cope. Texas, ? Mexico, ? Florida,® z.p. 
Fe (Dibelodon) shepardi, Leidy. California, Mexico, p. 
“p A cordillerarum,® Desm. S. America. 
an Mt tropicus, Cope. S. America and Mexico, p. 
“) humboldti, Cuv. S. America. 
Mastodon americanus, Cuv.’’ N. America. 
ii borsoni, Hays. Europe, p. 
ye faleonert, Lydd. India, p. 
+ mirificus, Leidy. N. America, zp. 
a sivalensis,® Cautley. India, p. 
1 Catalogue of Fossil Mammalia in the Brit. Mus., pt. iv. p. 72. 
* In compiling this list I have been greatly aided by the Memoirs of Lydekker in 
the “ Paleontologia Indica ’’ and the Catalogue of the British Museum. 
3 M. proevus, Cope, 1884, not 18738. 
4 According to Lydekker no premolars have been seen in this species. 
> M? floridanus, Leidy. 
6 M. andiwm, Cuv. According to the recent researches of Burmeister, this species 
does not possess mandibular tusks (Sitzungsb. Kén. Preuss. Akad. Wiss., Berlin, 
1888, p. 717). Hence the specimen from Mexico with such tusks, reported by 
Falconer, must be assigned elsewhere, 
7 This species is said by Lydekker not to possess premolars. Leidy, Report U.S. 
Geol. Surv. Terrs. Pl., figures a tooth as a premolar, and similar specimens are not 
uncommon, 
® According to Lydekker, premolars have not been observed. 
