618 LAND MAMMALS IN THE WESTERN HEMISPHERE 



With one br two exceptions, the plates of the carapace were not 

 arranged in transverse rows, but formed a mosaic without dis- 

 cernible banding. In the exceptions noted, the sides of the 

 carapace were made up of bands, and near the margins were 

 two or three overlapping transverse bands which permitted a 

 minimal degree of flexibility. The tail-sheath was remarkable 

 and differed much in appearance and make-up in the various 

 genera. In ^Glyptodon the tail was comparatively short and 

 the tail-sheath was made up of a series of overlapping rings, 

 each ring consisting of two rows of plates ; those of the second 

 row were ornamented, on the top and sides of the tail, with 

 very prominent, conical projections, capped, in the living ani- 

 mal, with still longer and sharper spines of horn, so that the tail 

 must have bristled with spikes. A more usual type of tail- 

 sheath was exemplified by \Sclerocalyptus, in which there were 

 several overlapping rings at the root of the tail, but for much 

 the greater part of its length the plates of the sheath were 

 fused together into a long, transversely oval tube, tapering 

 very gently to the free end, where it was bluntly rounded. A 

 modification of this type was the very long tail-sheath of 

 ^Panochthus, in which there were seven overlapping rings at 

 the root, followed by a long, massive tube, the sides of which 

 were set with three or more large and heavy, horn-like spines. 

 In ]D(edicurus was reached the maximum specialization of 

 this type ; the very long tube had its free end greatly expanded 

 and thickened into a huge, club-shaped mass, on the top and 

 sides of which were fixed long and sharp horns. 



The teeth, which in all the known genera numbered \, were 

 all very much alike ; each was divided by two broad and deep 

 vertical grooves on each side into three pillars, connected by 

 narrow necks. Harder dentine in the centre and on the pe- 

 riphery of the tooth, with a softer intermediate layer, kept the 

 grinding surface rough through differential wear. Teeth of this 

 character are indicative of a vegetable diet and these great crea- 

 tures were, no doubt, as harmless and inoffensive as possible. 



