GLYPTODONTIDiE. 115 



elongated. In the peripheral regions the central disks are larger 

 than in the dorsal region ; the grooves between the disks are deep, 

 and in the groove surrounding the central disk there are frequently 

 deep pits, which apparently contained hairs ; the surface of the 

 disks is always more or less rugose. The antero-inferior angles of 

 the carapace are not x^roduced in advance of the nuchal border ; and 

 the peripheral row of scutes form conical protuberances. At least 

 in those forms which have been generically separated under the 

 name of Schistopleurum^ the caudal sheath consists of a series of 

 movable rings ornamented with large conical tubercles, and has no 

 terminal tube. A ventral buckler is present. The fronto-nasal 

 region of the cranium has a straight profile. The humerus has no 

 entepicondylar foramen ; and there are five perfect digits in the 

 manus and four in the pes. 



If Owen's reference of the caudal tube to G, clavi^es be correct, 

 the genus Schistopleurum might be retained. 



Glyptodon clavipes, Owen \ 



The middle of the central disk of each scute of the carapace is 

 concave, with its rim raised above the level of the peripheral disks, 

 which are much smaller than the central one. The surfaces of the 

 disks are comparatively smooth, although pitted, and the intervening 

 grooves are wide and shallow. In the periphery of the carapace 

 the central disks of each scute become larger and elevated above 

 the peripheral disks. The scutes themselves are relatively larger 

 than in G. reticulatus, and the type specimen is of smaller size. 



The terminal tube of a caudal sheath appended to the type 

 carapace (woodcut, fig. 21) in the Museum of the Eoyal College of 

 Surgeons (No. 3584), and thus figured by Owen in pis. iv. and v. of 

 the Catalogue of the Possil Mammalia in that Collection as the 

 complete caudal sheath, resembles that of HopJoplioriis, to which 

 genus it is considered by Ameghino ^ that it belongs. The specimen 

 figured by Burmeister in the ' An. Mus. Buenos Aires,' vol. ii. 

 pi. xxxvi., under the present name has been referred by Gervais 

 and Ameghino to Hopulophorus ^. 



Hah. South America (Argentine Eepublic). 



1 In Parish's 'Buenos Ayres and La Plata,' p. Vi^i (1838). ^ 



2 Bob Ac. Nac. Cordova, vol. t. pp. 4, 20, 24, 25 (1883) ; seo also H. Gervais 

 and Ameghino, ' Maiumiferes Fossiles de I'Auierique Meridionale,' p. 203 

 (1880). Ameghino {pp. cit. pp. 24-5) states tliat a carapace has been found 

 associated with a caudal sheath like that ol' G. reticulatus. 



3 Vide infra, p. 133. 



i2 



