202 



E DENT A TA 



approximate in structure to those of the next family, so that the 

 genus tends to connect the Armadillos with the Glyptodonts. 



Family GLYPTODONTID.E. 



In the Pleistocene cavern -deposits of Brazil, but still more 

 abundantly in the fluviatile deposits which cover the country in the 

 neighbourhood of Buenos Ayres, are found the remains of some of the 

 most remarkable forms of mammals yet discovered, the Glyptodonts, 

 which may be regarded as forming a separate 

 extinct family. They differ from the existing 

 Dasypodidce in their large size, and in having the 

 carapace composed of a solid piece (formed by 

 the union of a multitude of bony dermal scutes) 

 without any movable rings, and in usually hav- 

 ing also a ventral piece or plastron. The facial 

 portion of the skull is very short. A long 

 process of the maxillary bone descends from 

 the anterior part of the zygomatic arch. The 

 ascending ramus of the mandible is remarkably 

 high. The teeth are in the known species, 

 all much alike, having two deep grooves or 

 flutings on each side, so as to divide them into 

 three nearly distinct lobes (Fig. 68). The verte- 

 bral column is almost entirely ankylosed into 

 a solid tube, and there is a complex joint at the 

 base of the neck, to allow of the head being 

 retracted within the carapace. The limbs are 

 very strong, and the feet short and broad, 

 resembling externally those of an elephant or 

 tortoise. This family is mainly characteristic 

 of the southern half of the American continent, 

 but some species of the type genus ranged into 

 Texas and Mexico. Many species of the family 

 have been described and figured, especially by 

 Burmeister (in the Annales del Museo publico de 

 Buenos Aires), among which the following may 

 be noticed. Hoploplwr^us is characterised by the sculptured and 

 frequently thin scutes of the carapace, those of the periphery being 

 flat, and not raised into prominences. The caudal sheath has 

 several overlapping movable rings at the base, and ends in a long 

 subcylindrical terminal tube similar to the one represented with the 

 carapace of Glyptodon in Fig. 69, which in all probability really belongs 

 to the genus under consideration. Each foot has four complete 

 digits, and the humerus has an entepicondylar foramen. Most of the 



FIG. 68. Tooth of Glyp. 

 todon from the side, and 

 from the grinding surface. 

 (After Owen.) 



