604 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 49. 



It is slightly shorter than the femur. The proximal end is divided 

 into two condyles which project posteriorly 

 and are separated by an intercondylar groove. 

 A well-developed prenemial crest projects from 

 the upper part of the shaft in front of the 

 internal condyle. The distal end is divided 

 into the two usual malleoh of which the inner 

 is the shorter and the heavier. These are 

 separated on the front by a shallow, vertical 

 groove. The flattened surfaces on the lower 

 anterior face of the bone was in contact with 

 the distal extremities of the fibula. Trans- 

 versely the distal surface of the tibia is angu- 

 larly convex. 



Measurements. ^^ 



Greatest length of tibia 300 



Greatest diameter proximal end, antero-posteriorly... 107 

 Greatest diameter distal end 77 



Fibula. — As usual the fibula is slender and 

 somewhat shorter than the tibia. It has a 

 flattened shaft, above which it becomes sub- 

 cyhndrical, below with a flattened posterior 

 face that lays against the opposing face of 

 the tibia (fig. 14). It has a greatest length of 

 276 mm. 



Pes. — In the pes of Thescelosaurus there are 

 four functional digits and one (the fifth) that 

 is vestigal. In the prehminary description of 

 this animal it was stated, "There are four digits 

 in the hind foot, metatarsal I being reduced; 

 digit V is wanting." More complete prepara- 

 tion of the hind foot, however, disclosed a rudi- 

 mentary fifth metatarsal attached to the pos- 

 terior side of metatarsal IV, as shown in fig- 

 ure 16. 



Tarsus. — The ossified tarsus is composed of 

 four elements, the astragalus and calcaneum 

 forming the proximal row, and two flattened 

 blocklike bones, that articulated with the proxi- 

 mal ends of metatarsals III and IV to form the 

 distal row. 



The astragalus, although closely applied to 

 the tibia, is not anchylosed with it. The cal- 

 caneum is higher than wide and articulates dis- 

 taUy, entirely with the outer tarsal element 



Fig. 14.— Right hind leg of 

 Thescelosaurus neglec- 

 Tus. Type. Cat. No. 7757, 

 U.S.N.M. About i nat. 



SIZE. FjaONT VIEW, SHOWN 

 AS rpjTND AETICPJ.AK'ED. 



