EDENTATA OF THE SANTA CRUZ BEDS. 147 



inclination of the zygomatic arch. The forehead and muzzle are more 

 convex on the dorsal side than those of Propalceohoplophorus australis. 



MEASUREMENTS. 



Cranium, length to rim of orbit 112 Zygoma, length 083 



" width over zygomata 105 " width behind postorbital process .025 



Occiput, height 046 Distance occipital condyle to glenoid 



" width at base 057 cavity 045 



Basioccipital, width posteriorly 030 Rostrum, width at base 041 



" " anteriorly 016 Palate, width at& 025 



Glenoid cavity, elevation above %- 045 



EUCINEPELTUS Ameghino. 



(Plates XXI, Figs. 2-4; XXIV, Figs. 9-11 ; XXVI, Fig. 9; XXIX, Figs. 1-5.) 



Eucinepeltiis Amegh., Rev. Argent, de Hist. Nat., T. I, 1891, p. 326. 

 Propalceohoplophoms Me'rcerat, in part; Rev. del Mus. de La Plata, T. 



II, 1891, p. 28. 



Propalceohoplophonis Lydekker, in part ; Anales del Mus. de La Plata, T. 



III, 1894, p. 45. 



A very distinct genus, which includes the largest glyptodonts yet dis- 

 covered in the Santa Cruz beds and may be readily recognized by the 

 peculiarities of the cephalic shield. Except for its larger size, the carapace 

 is not distinguished by any important characters of form, composition, 

 or -ornamentation from that of Propalceohoplophorus, save that all the plates 

 have a smooth, flat surface, and in none of them is the central figure 

 'raised into a low convexity, as it is in the hinder part of the carapace of 

 the last named genus. Another slight difference appears to be that in 

 Eiicinepeltus the lateral marginal plates are of more uniform width, mak- 

 ing the lateral borders smooth and non-serrate. 



On the other hand, the cephalic shield (Plate XXI, figs. 2-4) is alto- 

 gether different from that of any other contemporary genus ; it is a single 

 thick and massive bone, convex dorsally and concave ventrally and made 

 up by the fusion of the plates, which vary in number from eleven to fif- 

 teen, according to the species. The approximate edges of a number of 

 these plates, also varying according to the species, are raised into very 

 prominent, jagged ridges, with a line of conspicuous piliferous pits on 

 each side of the ridge. The surface of the plates is nearly smooth, finely 

 granular, or punctate, without any definite ornamental pattern, though 

 having a convexity in the centre, which, in a variable number of the plates 



