Sinclair: typotheria of the santa cruz beds. 
33 
Restoration of the Skeleton (PL VII). — Compared with Inter atherium 
(PI. IX), the restored skeleton of Protypotherium shows the proportionately 
greater length of the limbs. The hind feet have been given a digitigrade 
position because of the length, depth and sharpness of definition of the 
astragalar trochlea. The depth of the posterior portion of the thorax is 
conjectural, as are also the lengths of the spines of the median dorsals and 
cervicals. The tail has been drawn to scale from a much smaller speci- 
men, probably P. prcerutilum , in which eighteen free caudals are present. 
It may have been longer than is represented in the restoration. 
Species. — Three species are represented in the collections at Princeton 
University and the American Museum of Natural History (P. australe , 
prcerutilum , attenuatum ). Within the limits of each there is considerable 
range in size, all transitions occurring between the minimum for the 
largest species ( P '. australe ) and the maximum for the next smaller form ( P . 
prcerutilum ), making their separation a more or less arbitrary matter. P. 
attenuatum shows less range in size and is characterized by fairly well 
marked cranial peculiarities, by which it may be readily recognized. In 
the absence of detailed stratigraphic work, with systematic collecting from 
definite levels, it is impossible to avoid confusing individual variations 
with true mutations of specific value, and this may account for the diffi- 
culty in separating P. australe from P. prcerutilum. 
Protypotherium australe (Moreno) Ameghino. 
(Pis. Ill, Figs. 1-4; IV ; V, Figs. 1-3, 6-10, 16-20 ; VI, Figs. 7-10, 14, 15 ; VII ; Text Figs. 
lA, 2, 3A, 4A, 8.) 
Toxodontophanus australis Moreno ; Patagonia, resto de un antiguo con- 
tinente hoy submerjido, p. 23, 1882 ( nomen nudum). 
Protypotherium ( Toxodontophanus) australe Ameghino ; Observaciones 
generales sobre el orden de mamiferos estinguidos sud-americanos 
llamados Toxodontes, etc., p. 64, 1887. 
Patriarchies palmidens Amegh.; Contrib. al Conoc., etc., p. 481, PI. 15, 
figs. 2-3, 1889. 
Patriarchus furculosus Amegh.; Revista Argent, de Hist. Nat., I, p. 292, 
1891. 
Patriarchus distortus Amegh.; ibid., p. 293, 1891. 
Protypotherium distortum Amegh.; Enum. Syn., etc., p. 13, 1894. 
