Sinclair: typotheria of the santa cruz beds. 
47 
Metatarsal II, length 
“ III, “ 
“ IV, “ 
« v, “ 
Digit, III, first phalanx, length 
“ “ second “ “ 
“ “ ungual “ “ 
Digit IV, first “ “ 
“ “ second “ “ 
“ “ ungual “ “ 
No. No. No. 
9187. 15,665. 1 5,341 . 
.026 .0246 
•035 
•037 .036 
.0265 
.016 
.0113 
.01 1 
.0162 
.01 1 
.0105 
INTERATHERIUM (Moreno) Ameghino. 
(Plates VI, Figs. 11, 12, 13, 16-21 ; VIII, IX; Text Figs. 1 B, 11, 12.) 
Interatherium Moreno ; Patagonia resto de un antiguo continente hoy 
submerjido, p. 23, 1882 [no men mid uni). Ameghino; Observ. gen. 
sobre los Toxodontes, etc., p. 63, 1887. 
Icochilus Ameghino; Contrib. al Conoc., etc., pp. 469-474, 1889. 
Tembothevium Moreno; fide Ameghino, Observ. gen. sobre los Toxo- 
dontes; etc., p. 65, 1887. 
A large amount of material from localities near the east coast of Pata- 
gonia is referable to this genus. All parts of the skeleton are well 
represented. 
Dentition (PI. VIII, figs. 16, 18, 20-27). — The dental formula varies 
slightly, owing to the loss in some individuals of the lateral incisor and 
occasionally the canine, and the presence in others of supernumerary teeth. 
The median incisors are enlarged and functional as cropping teeth. The 
crown continues to grow more or less during life, but in old individuals 
the width of the crown rapidly decreases above the alveolar border. 
The enamel layer, in worn specimens, is confined to the anterior surface. 
If any is present on the inner side of the crown, it must extend but a short 
distance above the cutting edge, as none is here observable in little-worn 
teeth. The crown of the second incisor is smaller and lower than the 
first with the enamel layer also external. The margins of the cutting 
edges of the first and second incisors are closely applied without imbrica- 
tion, forming a perfectly symmetrical crescent. The third incisor is still 
smaller. In certain individuals it is well developed in proportion to its 
