EDENTATA OF THE SANTA CRUZ BEDS. 37 



imating to the view that the family should be regarded as a closely 

 connected phylogenetic series, together with such short side-branches as 

 did not themselves become extensively ramified. On this view, Stego- 

 tlieriuni should be included among the Tatuidce, to which it is evidently 

 allied and of which it forms a side-branch that never at any one period 

 became greatly varied or widely ramified into numerous genera. In the 

 Santa Cruz beds representatives of this genus are comparatively rare and, 

 so far as is yet known, the entire series became extinct at the close of that 

 epoch, for no member of it has been found in any of the subsequent 

 formations. 



STEGOTHERIUM TESSELATUM Ameghino. 



(Plates I-IV.) 



Stegotherium tesselatum Amegh. ; Enumeracion sistematica, etc., p. 25. 

 Peltephilus strepens Lydekker, in part ; Anales del Museo de La Plata, 



T. Ill, 1894, p. 68. 



This species was established upon isolated scutes of the carapace, which 

 agree so well with those of the two specimens in the Princeton collection 

 that I have no hesitation in assigning them to it. The preceding account 

 of the osteology of the genus is drawn from those two individuals and it 

 only remains to give the principal measurements. 



MEASUREMENTS. 



No. 15,515. No. 15,566. 



Skull, length on median basal line 120 



" " occipital condyle to end of rostrum 139 



Cranium, length to anterior border of orbit 049 .050 



Face, length 090 



Occiput, height 036 .036 



" width at base 040 ? .042 



Skull, width over lachrymals 038 ? .042 



Rostrum, width at hinder end of nasals 021 ? .023 



anterior end 0105 



Mandible, length ? . 109 .107 



" " angle to last tooth ? .047 -0455 



" of edentulous part 048 .046 



" height of coronoid process 016 .014 



" " " " condyle 0145 



" depth of horizontal ramus at last tooth 006 .006 



" thickness of ramus at last tooth 0035 .003 



Upper dental series, length 01 15 .0105 



Lower " " " 015 .014 



