EDENTATA OF THE SANTA CRUZ BEDS. 135 



i 



genus departs from the later and more specialized glyptodonts, it approxi- 

 mates the armadillos. As we trace the two orders back in time, they 

 converge toward a common type and it seems abundantly clear that both 

 were derived from the same stock. 



Species. Ameghino has distinguished three species of this genus, P. 

 australis, P. incisivus and P. minor, and to these Mercerat has added a 

 fourth, P. aratrce. The first two shade into each other by such impercep- 

 tible gradations that it seems impossible to separate them ; it is true that 

 from a considerable series of skulls typical examples may readily be se- 

 lected which are quite distinct, but the number of intermediate specimens 

 quite equals that of the typical ones. P. aratrce is very imperfectly 

 known, but there seems to be no reason for separating it from P. australis. 

 On the other hand, P. minor is apparently well distinguished ; at all 

 events, the transitions are neither so numerous nor so closely connected. 



PROPAL^EOHOPLOPHORUS AUSTRALIS (Moreno) Ameghino. 



(Plates XVIII, XXI, Fig. i ; XXII, XXIII, XXIV, Figs. 1-6; XXV, 

 Figs, i, 5-10 ; XXVI, Figs. 2-8.) 



Hoplophorus aiistralis Moreno ; Patagonia, Resto de un antiguo Conti- 



nente hoy Submergido, 1882, p. 26. 



Propalceohoplophorus australis Amegh. ; Enum. sistem., 1887, p. 24. 

 Propalceohoplophorus incisivus Amegh. ; Ibid. 

 f Propalceohoplophorus aratrce Mercerat ; Rev. del. Mus. de La Plata, T. 



II, 1891, p. 40. 



This species is quite variable in regard to the form, size and position 

 of the anterior teeth, the length of the rostrum, the prominence of the 

 frontal sinuses, and such minor details, but in essentials the species is 

 very constant. In the posterior upper teeth the division of the postero-ex- 

 ternal lobe is relatively faint. The skull is large in proportion to the size 

 of the animal, narrow and elongate, the convexity of the forehead is but 

 moderate and the rostrum, though variable, is always relatively long, so 

 that the upper profile of the skull makes a long and gradual descent from 

 the parietal eminence to the end of the muzzle ; the rostrum contracts 

 anteriorly and has quite a deep fossa on the maxillary just in front of the 

 zygomatic process. The zygomatic arches are long, but do not extend 

 out very far from the sides of the cranium, making the temporal openings 



