Sinclair: typotheria of the santa cruz beds. 
85 
No. 
No. 
No. 
I5A3I ■ 
15,298. 
I 539 2 
Tibia + fibula, greatest transverse diameter proximally. 
.029 
.029 
it U (( tl 
distally 
.0245 
.026 
Calcaneum, length .... 
.038 
.038 
Astragalus, length .... 
.0195 
.020 
“ greatest width of body . 
.0165 
.016 
“ width of head 
.008 
.0085 
Metatarsal II, length 
•0395 
“ width of proximal end 
.0077 
“ “ distal “ 
. 
.009 
Metatarsal III, length 
.0426 
“ width of proximal end 
.0075 
“ “ distal “ 
.008 
Metatarsal IV, length 
.038 
width of proximal end 
.0065 
“ “ distal “ 
.0065 
Metatarsal V, length 
.0273 
“ width of distal end 
.003 
PACHYRUKHOS Ameghino. 
(Plates X, XI ; Text Fig. I, C.) 
Pachyrukhos Amegh.; Nuevos restos de mam. fos., etc., Bol. Acad. Nac. 
Cien. Cordoba, VIII, entr. 1, pp. 160-162, footnote, 1885. 
Pachyrucos Amegh.; Contrib. al Conoc., etc., pp. 422-436, 918, 1889. 
Pcedotherium Burmeister; Anales del Mus. Nac. de Buenos Aires, T. Ill, 
p. 179, 1888 [fide Ameghino). 
This genus includes the smallest representatives of the Typotheria in 
the Santa Cruz beds. Like Hegetotherium , to which it is closely related, 
but one recognizable species appears to be present. Three almost com- 
plete individuals are preserved in the American Museum collection, illus- 
trating all parts of the skeleton except the anterior dorsal region, and on 
these the following description is based, supplemented wherever possible 
by the less complete material in the Princeton collection. 
Dentition (PI. X, figs. 1, 3, 13). — As in Hegetotherium , the median 
upper incisors are greatly enlarged, cropping teeth, growing persistently, 
and supported entirely by the premaxillae. In the moderately worn speci- 
mens studied the enamel is confined entirely to the anterior surface of the 
crown. The remaining incisors, the canine and the first premolar are 
entirely wanting, producing a long diastema between the median incisor 
