scott: toxodonta OF THE SANTA CRUZ beds. 
237 
Pal/EOLIthops pr^evius Ameghino. 
Litliops prcevius Amegh.; Enum. sistem., etc., 1887, p. 15. 
Palceolithops prcevius Amegh.; Rev. Argent, de Hist. Nat., T. I, 1891, 
p. 241. 
ACROTHERIUM Ameghino. 
(See pp. 181, 233.) 
Acrotherium stygium Ameghino. 
Acrotherium stygium Amegh.; Rev. Argent, de Hist. Nat., T. I, 1891, 
p. 133. 
XOTOPRODON Ameghino. 
Xotoprodon Amegh.; Rev. Argent, de Hist. Nat., T. I, 1891, p. 241. 
Xotoprodon solidus Ameghino. 
Xotoprodon solidus Amegh.; Rev. Argent, de Hist. Nat., T. I, 1891, 
p. 241. 
Xotoprodon maximus Ameghino. 
Xotoprodon maximus Amegh.; Rev. Argent, de Hist. Nat., T. I, 1891, 
P- 375- 
NO TOHIPPIDAi. 
NOTOHIPPUS Ameghino. 
Notohippus Amegh.; Rev. Argent, de Hist. Nat., T. I, 1891, p. 63 ( nomen 
nudum), Ibid., p. 135. 
Nesodon Burmeister, in part; Anal, del Mus. Nac. de Buenos Aires, T. 
Ill, fasc. XVIII, 1892. 
Notohippus toxodontoides Ameghino. 
Notohippus toxodontoides Amegh.; Rev. Argent, de Hist. Nat., T. I, 
1891, p. 63 ( nomen nudum), Ibid., p. 135. 
Nesodon ovinus Burmeister, in part ; Anal, del Mus. Nac. de Buenos 
Aires, T. Ill, fasc. XVIII, 1892. 
This very interesting, but imperfectly known, species is remarkable for 
having the lower molars surrounded by an uninterrupted wall of enamel 
and having the crowns covered by a thick layer of cement (“por un grueso 
deposito de cemento”). Originally, Ameghino referred the genus to the 
