92 PATAGONIAN EXPEDITIONS! PALEONTOLOGY. 



nasals are quite unusually thick and stout ; at the anterior end, they extend 

 somewhat beyond the premaxillae, are broadened and gently decurved. 

 The premaxillaries are small, but the ascending ramus has its dorsal end 

 considerably produced forward in a semicylindrical process ; the alveolar 

 portion is quite high and thick, presenting forward, with a median spine- 

 like projection ; the palatine processes are exceedingly small and no dis- 

 tinct incisive foramen is visible. The anterior nares are large, terminal 

 and cordiform, broad dorsally, contracting much ventrally. 



The maxillary is much shorter than in other Santa Cruz armadillos and 

 its facial portion, which is of more uniform dorso-ventral height, is made 

 convex by the sockets of the teeth, especially of ^ and - ; the zygomatic 

 process is a prominent and heavy plate, with flat side directed forward ; 

 the infraorbital canal is very short and has an inferior position ; the 

 alveolar process is high and projects well below the level of the hard 

 palate, which is thus vaulted and concave in both directions and its gen- 

 eral shape is that of an elongate horse-shoe, contracting behind. The 

 palatines are large and contribute extensively to the formation of the hard 

 palate, reaching forward to the line of & and, posteriorly, far behind the 

 teeth ; the margins, both in the maxillary and palatine regions, are per- 

 forated by numerous small vascular foramina. The posterior nares are 

 small, and very low, and are placed unusually far back, not only with 

 reference to the short dental series, but also in relation to the orbit and 

 other parts of the skull. The pterygoids are small, without fossae, or 

 hamular processes. 



One of the most peculiar parts of this remarkable skull is the mandible, 

 the two rami of which are completely coossified at the symphysis, and the 

 short, curved jaw, in a single piece, has considerable resemblance to that 

 of a turtle. The horizontal ramus is short, incurved anteriorly to meet 

 its fellow of the opposite side, compressed, but deep vertically ; the sym- 

 physis is very short and steeply inclined and the chin abruptly rounded ; 

 the ascending ramus is very low, but with large well-defined masseteric 

 fossa ; the condyle is almost sessile and has a very inferior position, in 

 some cases even below the level of the teeth, a very decided difference 

 from all other Santa Cruz armadillos, except Stegotlieriiim ; the angular 

 process is a short, blunt hook. 



The cranial foramina are not especially peculiar ; the optic foramen and 

 foramen lacerum anterius are enclosed in a common deep depression of 



