134 PATAGONIAN EXPEDITIONS: PALAEONTOLOGY. 



sion than the laterals (I and V). In the latter the unguals are relatively 

 long and bluntly pointed, but in the median three they are very broad and 

 hoof-like. 



Restoration (Plate XXII). The general appearance of the skeleton 

 suggests a small and very lightly built Glyptodon; the shape of the skull, 

 the length of the neck, the curvature of the back, the proportions of the 

 tail, and the relative lengths of the fore- and hind-limbs most nearly re- 

 sembling those of the last named genus. On the other hand, the bones 

 of the limbs and feet have the more slender proportions seen in Sclero- 

 calyptus, to which many resemblances of detail may be observed. A 

 notable difference from the Pampean genera is in the much smaller verti- 

 cal diameter of the head and the far less elevated position of the occipital 

 condyles, in consequence of which the skull depends less below the level 

 of the neck. It is unnecessary to repeat here the details of resemblance 

 and difference, to which attention has been called in the foregoing de- 

 scription. The most significant feature is the unmistakable similarity to 

 the armadillos, to which group the present genus is distinctly nearer than 

 are the great Pampean types. 



Relationships. Mercerat ('91, 33) and Lydekker ('94, 47) have pointed 

 out the many resemblances between this genus and the later Plohophorus. 

 Lydekker expresses the opinion, "that Propalczohoplop horns was either 

 the direct ancestor of Plohophorus, or was very nearly related to such an- 

 cestor. Possibly the ancestral form may have been another species, with- 

 out imbricating bands in the margin of the carapace. The genus was 

 likewise not improbably related to the ancestral stock from which Glyp- 

 todon originated" (loc. cit.\ 



It seems altogether likely that the Santa Cruz genus was very near to 

 the common stem whence all the Pampean types arose by divergent de- 

 velopment, but none of the latter, so far known, appears to be directly 

 descended from it. On the other hand, a North American representative 

 of this series very probably persisted into the Pleistocene. The fine cara- 

 pace collected in Texas by Mr. Gidley, for the American Museum of 

 Natural History, which Osborn has described ('03, 489) under the name of 

 Glyptotheriiim texanum, has associated with it a tail-sheath of quite similar 

 character to that of Propalceohoplophorus, but no representative of this 

 series has yet been found in the Pleistocene of South America. It is a 

 highly suggestive fact that, in those respects in which the Santa Cruz 



