Sinclair: typotheria of the santa cruz beds. 
ioi 
three grooves of which the median one is much broader and the other 
two very narrow (’94, 16). 
Interatherium anguliferum Ameghino. 
Interatkerium anguliferum Amegh. ; Enum. Synoptique, etc., p. 18, 1894 ; 
Segundo Censo, etc., p. 151, 1898 (listed). 
Size intermediate between /. rodens and /. supermini from which it is 
distinguished by the absence of the first upper premolar. The upper 
canine is well developed and isolated by diastemata in front and behind. 
P-- A have the two perpendicular columns of the antero-external angle 
very strong. Length from the anterior border of the canine to the pos- 
terior border of the first upper true molar .017 (’94, 18). 
Interatherium anomalum (Ameghino). 
Icochilus anomalus Amegh.; Enum. Synoptique, etc., p. 16, 1894; Se- 
gundo Censo, etc., p. 15 1, 1898 (listed). 
Of the same size as Icochilus extensus. This species is easily dis- 
tinguished by the atrophy and disappearance of many teeth. The ex- 
ternal lower incisor is very small. The lower canine is extremely small 
and isolated before and behind by diastemata of considerable length, 
while in almost all the other species of this genus this tooth is, on the 
contrary, well developed and recumbent on the incisors of which it has the 
form. The first lower premolar is well developed, with two opposite per- 
pendicular grooves, one internal and the other external (’94, 16). 
Interatherium truncum (Ameghino). 
Icochilus truncus Amegh. ; Enum. Synoptique, etc., p. 16, 1894; Segundo 
Censo, etc., p. 151, 1898 (listed). 
Almost of the same size as Icochilus extensus. It is distinguished by 
the presence of a very small first lower premolar, and by the absence of 
the lower canine. In the place of the canine there is quite a long dia- 
stema which separates the external incisor from the first premolar (’94, 16). 
Interatherium undulatum (Ameghino). 
Icochilus undulatus Amegh.; Contrib. al Conoc., etc., p. 473, PI. 15, fig. 
14, 1889; Enum. Synoptique, etc., p. 15, 1894 (listed); Segundo 
Censo, etc., p. 150, 1898 (listed). 
