4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 6l 



surface extending' the entire length of the centrum, being wider 

 behind than in front. Cervical ribs free. Dorsal ribs of good length, 

 T-shaped above but flattening out into a broad distal portion. Cal- 

 cified sternal ribs present. 



In the pectoral arch the scapula is remarkably short with widely 

 expanded blade, much as in Camptosaurus (see fig. 2). The proxi- 

 mal portion of this bone not known. Ossified sternum present. Only 

 the distal half of the humerus known, but the proportions between 

 upper and lower bones of the fore limb appear much the same as in 

 other bipedal predentate dinosaurs. Carpus ossified, though its ele- 

 ments have not yet been definitely determined. There are five digits in 

 the manus, having the phalangial formula 2, 3, 4, 3, 2. The first three 

 digits are tipped with pointed unguals, the terminals of the fourth 

 and fifth, however, have been reduced to small rounded bony nodules ; 

 the fifth digit is borne by a small metacarpal and is comparatively 

 feeble. Ungual digit II missing. 



The pelvic arch has not been developed sufficiently to show all its 

 features, but the presence of a rounded rod-like pubis with a long, 

 slender postpubic process reaching the end of the ischium is observed. 

 The ischia have flattened shafts meeting on the median line but with- 

 out especial enlargement of their distal ends. 



The femur is longer (355 mm.) than the tibia (300 mm.), slightly 

 curved and with pendant trochanter on the postero-inner face of the 

 shaft. As in Camptosaurus this trochanter is developed just above the 

 middle of the shaft. The finger-like great trochanter is present on 

 the antero-external angle of the proximal end. The head is globular 

 and separated from the shaft by a well-defined neck. Fibula slender 

 with distal third closely applied to the tibia. 



The astragulus and calcaneum as usual form the proximal row of 

 the tarsus. The distal row consists of two flattened bones articulating 

 with the proximal ends of metatarsals III and IV, the inner element 

 extending somewhat over the top of metatarsal IV, as shown in figure 

 4 of the articulated foot. There are four digits in the hind foot; 

 metatarsal I being reduced; digit V is wanting. The phalangial 

 formula is 2, 3, 4, 5, o. All digits are terminated by pointed claw-like 

 unguals. 



Typically Thescelosaurus neglectus is of moderate size, having a 

 total length of perhaps twelve feet, and standing a little over three 

 feet at the hips. The fore-limbs are somewhat more than half as long 

 as the hinder pair, and this disproportionate length of limb would 

 appear to indicate an animal normally using a bipedal mode of pro- 

 gression. 



