70-4 INDIAN TERTIARY AND POST-TERTIARY YERTEBRATA. 
therium and JE quits, we may confine our attention in this memoir to the considera- 
tion of those two genera, and, in order to obviate the necessity of quoting synonyms 
in the sequel, the following list of all the named species of the two genera with 
which I am acquainted has been drawn up. This list indicates the synonomy, 
and, in a general way, the geological and geographical distribution of each species. 
Doubtful species are indicated by an asterisk, while a note of interrogation indicates 
those instances where there may be doubt as to the identification of a synonym. 
Genus I: HIPPOTHERIUM, Kaup. 
Synonyms — Eipparion (Christol), Hippodon (Leidy), Sivalhippus (Lydekker). 
1. Hippotherium afeine (Leidy sp.). N. America; pliocene. 
Eipparion affine (Leidy). 
2. Hippotherium antilopinum (Ealc. and Caut.). India and (?) China; Mio- 
pliocene. 
Equus primigenius (Von Meyer). 
Eipparion antilopinum (Gaudry) . 
3. Hippotherium calamarium (Cope). N. America ; pliocene. 
4. Hippotherium gracile (Kaup.). 1 Europe and (?) N. Africa; miocene. 
Equus angusticlens (Meyer). 
„ asinus primigenius (Meyer). 
„ caballus (Meyer) . 
„ gracilis (Kaup). 
„ mulus primigenius (Meyer) . 
„ nanus (Kaup). 
„ primigenius (Meyer) . 
Eipparion diplostylum (Gerv.). 
„ gracile (Christol). 
5. Hippotherium gratum (Leidy. sp.). 
Eipparion gracile, var. m.editerraneum ( Roth, 
and Wag.) 
„ mediterraneum (Hensel) . 
„ mesostylum (Gerv.). 
„ prostylum (Gerv.). 
Hippotherium mediterraneum (Kaup). 
„ meridionale (Kaup) . 
„ nanum (Kaup) . 
N. America ; pliocene. 
Eipparion gratum (Leidy). 
6. Hippotherium occidentale (Leidy). N. America; pliocene. 
Eipparion occidentale (Leidy). 
7. Hippotherium paniense (Cope). N. America; pliocene. 
8. Hippotherium speciosum (Leidy sp.). N. America; pliocene. 
Eipparion speciosum (Leidy) . | Hippodon speciosus (Leidy) . 
9. Hippotherium theobaldi (Lydekker). India and (?) China; mio-pliocene. 
(?) Equus primigenius (Meyer) ; [ Sivalhippus theobaldi (Lydekker). 
Eipparion theobaldi (Blanford). | 
1 I follow M. Gaudry in uniting H. mediterraneum with H. gracile (see “ Animaux fossiles du Mt. Leberon,” 
p. 32). M. Hansel still considers the two species to be distinct. (See “ Abhand. d. k. Akad. d. Wissen. z. Berlin” 1861, 
p. 27). The only distinction between the two so-called species seems to be a slight difference in the size of the molars 
and in the folds of the enamel in the lower molars. 
