PROEUPHRACTUS 203 
plates in the pelvic buckler (11), and in details throughout 
the skeleton. We found no representatives of the genus, 
but Ameghino has described a species (no figure), S. 
(Prodasypus) ornatus* based on isolated plates. A moy- 
able plate measures 18 mm. long by 6-7 mm. wide, while 
a fixed plate measures 9 mm. long, by 6-7 mm. wide. 
Proeuphractus Ameghino 
Proeuphractus Amegh., 1886, Bol. Acad. Nac. Cienc. Cordoba, t. 9, p. 208. 
This genus is seldom found, but is distinguished by Ame- 
ghino by the absence of a pelvic buckler, all the plates of the 
crapace being movable. From the Deseado beds, Ameghino 
describes two species, P. setiger and P. laevis, both based on 
isolated plates; the former distinguished by having no pilif- 
erous perforation in the furrows surrounding the central 
figure, and with well-developed pitson the posterior margin; 
while the latter has small piliferous perforations in the fur- 
rows and only rudimentary ones on the posterior margin. 
These features do not seem to me to distinguish species. 
In addition to the foregoing, Ameghino has made a 
series of genera and species,t Archaeutatus, Amblytatus, 
Isutaetus, Sadypus, Hemiutatus, Anutaetus, all based on 
isolated plates, and distinguished by variations in the 
central figure and the piliferous pits. I am unable to find 
a satisfactory basis for distinguishing the genera or species, 
and feel that, until more complete material is known, it is 
impossible to say which are valid genera or species. 
Peltephilus Ameghino 
Peltephilus Amegh., 1887, Bol. Mus. La Plata, t. 1, p. 25 of separate. 
Cochlops Amegh., in part, 1889, Act. Acad. Nac. Cienc. Cordoba, t. 5, p. 792. 
Gephyranodon Amegh., 1891, Revista Argen., Hist. Nat., t. 1, p. 119. 
? Anatiosodon Amegh., 1891, Revista Argen. Hist. Nat., t. 1, p. 327. 
Peltephilus Scott, 1903-5, Princeton Patagonian Exped., vol. 5, p. 88. 
While rare, this genus is well known from the Santa 
Cruz, and is characterized by the curious development of 
* Bol. Inst. Geog. Argen., t. 18, p. 508, 1897. 
+ Bol. Acad. Nac. Cienc. Cordoba, t. 17, p. 56-66, 1902, no figures. 
