46 PATAGONIAN EXPEDITIONS I PAL/EONTOLOGY. 



terior projection. The posterior cornu consists of a single element, the 

 thyro-hyal, which is fused with the basi-hyal and is elongate and much 

 more slender than the proximal element of the anterior cornu ; its proxi- 

 mal end is slightly thickened and club-shaped, while the remainder is 

 laterally compressed. 



As in Dasypus, the thyroid cartilage is completely ossified into a very 

 thin, but dense and smooth bone, which forms somewhat more than half 

 of a hollow cylinder and lies, apparently in its natural position, against 

 the ventral side of the axis ; the posterior border has a deep median notch. 

 On the dorsal side, near the hinder end, the bone is perforated by a pair 

 of small foramina, which were probably for the passage of the laryngeal 



nerves. 



MEASUREMENTS. 



Cranium, length to anterior rim of orbit.. .065 Forehead, width 057 



" width at zygomatic processes.. .056 Mandible, depth below y 017 



Occiput, height 041 " thickness below y oio 



" width at base 046 " width of ascending ramus 030 



" " across condyles 040 height of condyle 042 



Vertebral Column.- -In the type-specimen the backbone is complete to 

 and including the first sacral. As a whole, the presacral region is short 

 and massive, resembling that of Dasyptts, but on a much larger scale. 

 The neck is short and, in its usual position, directed steeply downward 

 and backward and making a sharp angle with the thoracic region, which 

 rises very abruptly in the anterior part and is strongly curved. For the 

 rest of its course the thoracic region is moderately curved, while the loins 

 are short, heavy and nearly straight. The sacrum, as is shown by other 

 specimens, is very long and the tail, which is imperfectly known, is rather 

 short but stout. The vertebral formula is : C 7, Th 1 1 , L 3, 89. 



The atlas is short longitudinally and very broad transversely. As in 

 most armadillos, the sides are high and are nearly at right angles with the 

 neural and inferior arches ; the former arch is broad but deeply emar- 

 ginated between the anterior cotyles and the spine is almost obsolete. 

 The anterior opening of the vertebrarterial canal is a conspicuous foramen 

 on the side of the atlas. The transverse processes are like those of Dasy- 

 pus, but relatively better developed. 



The axis is coossified with the third and fourth cervicals and the com- 

 pound mass is shorter than in Stegotherium, with broad depressed centra, 



