44 
PATAGONIAN EXPEDITIONS : PALEONTOLOGY. 
Protypotherium attenuatum Ameghino. 
(Pis. Ill, Figs. 5-7 ; V, Figs. 4, 5 ; VI, Figs. 1-6.) 
Protypotherium attenuatum Amegh.; Enumeracion Sistematica, etc., p. 15, 
1887. 
Protypotherium globo sum Amegh.; Revista Argentina, etc., p. 291, 1891. 
Protypotherium icochiloides Amegh.; Enumeration Synoptique, etc., pp. 
14-15, 1894. 
Patriarchus rectus Amegh.; Revista Argentina de Hist. Nat., I, p. 293, 
1891. 
Protypotherium attenuatum may be readily distinguished from the other 
species by its smaller size (length of skull .08-09 as contrasted with 
.099-112 in P. australe), and the marked convexity of the brain-case just 
posterior to the fronto-parietal suture, a character used by Ameghino in 
defining P. globo sum, a species here regarded as synonymous with P. 
attenuatum. A careful comparison of the skeleton, so far as known, with 
that of P. australe fails to show characters of specific value, apart from 
size. P. icochiloides was originally defined as transitional to the genus 
Icochilus [Inter atherium). The molars and premolars are said to be like 
those of Protypotherium , but the mandible is stout, with the horizontal 
ramus short, low in front and very high behind. The measurements 
accompanying the description agree closely with the dimensions of the 
mandible in No. 9187 Am. Museum (PI. Ill, fig. 6) which has been 
referred to P. attenuatum , and the two species are regarded as syn- 
onymous. Specimens in the Munich collection determined by Ame- 
ghino as P. icochiloides and Patriarchus rectus are certainly the same as 
P. attenuatum. 
The latter is represented in the Princeton and American Museum col- 
lections by a considerable amount of material illustrating the structure of 
the skull and limbs. The following localities have afforded specimens : 
Killik Aike (4), two miles west of Killik Aike, Rio Gallegos (1), south of 
Santa Cruz (1), ten miles south of Coy Inlet (1), five miles south of Coy 
Inlet (1), Coy Inlet (1). 
Nos. 15,665, 15,341, and No. 9187 American Museum, are illustrated 
in the accompanying plates. 
