286 MAMMALIA. 



humerus ; the maims has only four digits. The femur exhibits the third 

 trochanter just above the outer distal condyle ; the tibia and fibula are 

 remarkably short, and anchylosed together at their extremities ; the pes 

 has five complete digits, and the calcaneum is relatively large. There is a 

 head-shield of thin polygonal plates, and the carapace (fig. 163) is robust, 

 quite rigid, and usually ornately sculptured. One specimen in the Museum 

 of La Plata exhibits horny epidermal plates covering the bone, and the 

 arrangement of these corresponds exactly with that of the tesserae they 

 cover. They are not pierced by the foramina which so frequently pass 

 through the bones, thus indicating that the latter are vascular canals and 

 not for the insertion of hairs. The tail is relatively short and tapering, 

 and its bony sheath comprises a series of elliptical rings gradually di- 

 minishing in size and eccentricity towards the extremity (the tail-sheath 

 represented in the original restorations of Olyptodon thus belongs to 

 another genus). The typical species is Glyptodon clavipes from the 

 Pampa Formation (Pleistocene) of Buenos Aires, attaining a total length 

 of not less than four or five metres. 



Dsedicurus. This genus comprises the largest and most specialized 

 Glyptodonts. The skull is much like that of Glyptodon, but the orbit is 

 separated from the temporal fossa by a bar of bone, and the descending 

 zygomatic process is relatively shorter. The humerus has an entepicondy- 

 lar foramen, and the maims seems to have consisted only of three digits, 

 each with a broad claw. The pes comprises four digits, the three inner- 

 most with very broad claws, the outermost small and without a claw. 

 The head-shield is unknown. The carapace is smooth, and the scutes 

 are pierced by numerous and large vascular foramina. The tail is 

 relatively long, and the proximal part of its sheath consists of about 

 six rings of scutes like those of the carapace, while its distal part is a 

 much-depressed tube, somewhat expanded at the extremity where it 

 seems to have been ornamented with great bosses. The typical species 

 is Dcedicurus davicaudatus, from the Pampa Formation (Pleistocene) of 

 Buenos Aires. Smaller forms occur in the slightly earlier deposits near 

 Parana and in Monte Hermoso, near Bahia Blanca. 



A fragment of ornamented tessellated dermal armour, of 

 comparatively small size, from the Upper Eocene Phosphorites 

 of southern France, has been compared with the carapace of 

 the armadillos, and named Necrodasypus gallice. The deter- 

 mination, however, is extremely doubtful. 



Concerning the ancestry and true relationships of the 

 problematical Edentata of the Old World, Palaeontology as yet 

 furnishes no information. One humerus (named Necromanis 

 quercyi) from the French Phosphorites just mentioned is very 



