606 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 49. 



Metatarsal V is shown in figure 16, and is a small flattened bone 

 constricted at the middle, with sUghtly expanded ends. It probably 

 did not support any phalanges. 



Phalanges. — The digits have, respectively, two, three, four, and five 



phalanges, corresponding in number with most other bipedal dinosaurs. 



The proximal phalanx of digit I is especially elongated, as in 



Brachyceratops. The ungual of this toe is broken, but judging from 



the remaining proximal half it appears to have 



been short and bluntly pointed. 



The relative proportions of the remaining 

 phalanges are remarkably similar to those of 

 Camptosaurus. 



Viewed from above, the phalanges have ver- 

 tically concave proximal and convex distal 

 ends. Excepting the proximal ends of the first 

 row, all of the joints are broadly keeled, thus 

 forming strong articulating joints, that would 

 be proof against lateral dislocation. Well- 

 defined pits are present for the attachment of 

 tlie lateral ligaments. The imgual phalanges 

 are curved, of moderate length, and more de- 

 pressed than in Camptosaurus. They are rela- 

 tively shorter and less sharply pointed than 

 in Hypsilopliodon. The lateral grooves for the 

 external claw are well defined. 

 The pes of Thescelosaurus may be distinguished at once from the 

 hind feet of either Dryosaurus or Laosaurus by the greater elongation 

 of the metatarsals in those genera. In Thescelosaurus the greatest 

 length of metatarsals I, II, III, and IV is less than the total lengths 

 of the articulated phalanges of those digits. In Hypsilophodon this 

 condition prevails in digits III and IV, but in digit I the metatarsal 

 exceeds the phalanges in length, wliile in Drysaurus and Laosaurus the 

 metatarsals exceed the phalanges in this measurement. In its gen- 

 eral proportions the pes of Thescelosaurus resembles that of Campto- 

 saurus closer than it does that of its nearest relative Hypsilophodon. 

 Measurements of hind foot of No. 7757, U.S.N.M. 



Fig. 16.— Metatarsals of 

 eight hind foot of thes- 

 celosaurus neglectu3 

 GiLMOKE. Type, No. 7757, 

 u.s.n.m. \ nat. size. 

 Viewed from the back, 



AS shown as found ARTIC- 

 ULATED. I, II, III, IV, 

 AND V, METATARSALS ONE 

 TO FIVE. 



Digits. 



II. 



IV. 



V. 



Greatest 

 Greatest 

 Greatest 

 Greatest 

 Greatest 

 Greatest 

 Greatest 

 Greatest 

 Greatest 



length of metatarsals 



antero-posterior d iameter , prox imal end of metatarsals-. 



transverse diameter, proximal end of metatarsals 



transverse diameter, distal end of metatarsals 



length first row phalanges 



length second row phalanges 



length third row phalanges 



length fourth row phalanges 



length fifth row phalanges 



vim. 

 112 



mm. 

 127 



1 46 

 38 

 35 

 54 



mm. 

 106 

 28 

 41 

 23 

 35 

 26 

 22 

 19 

 40 



1 Measurement from another individual (No. 7758) of same proportions. 



