APPENDIX. 



r. LI. — Distinctive Characters of the order Hallopoda- y 



by O. C Marsh. 



In is 77. the writer described a small reptile from the 

 Jurassic of Colorado, and referred it to the Dinosauria* On 

 further investigation, it was found to be distinct from all the 

 known members of that group, and in 1881, it was made the 

 type of a new sub-order, the Hatlopoda.f One of the most 

 distinctive characters, which separated it widely from all 

 known Dinosaurs, was seen in the tarsus, which had the cal- 

 caneum much produced backward. This feature, in connection 

 with the greatly elongated metatarsals, suggested the generic 

 name HaUopus, or leaping foot. 



The general structure of the pelvis, especially of the ilium 

 and pubis, as well as the proportions of the entire hind limb, 

 suggested an affinity with Oompsognathus, from the Jurassic 

 of Bavaria, and the writer, in his classification of the Dino* 

 saurs, in 1882, placed the Hallojpoda next to the sub order 

 ComjMognatha, which belongs in the great group of carnivorous 

 Dinosaurs, the Theropoda.\ 



Quite recently, the writer has reexamined the type specimen, 

 and had various parts of it uncovered, so far as the hard matrix 

 of red sandstone would permit, This has brought to light 

 other portions of the skeleton, so that now many of the more 

 important characters of the order can be determined with 

 certainty. 



In its present condition, the specimen show T s both the fore 

 and hind limbs in good preservation, portions of the scapular 

 arch, and apparently the entire pelvis, and sacrum, various 

 vertebrae, ribs, and other parts of the skeleton. It is at present 

 doubtful if any portions of the skull are sufficiently well 

 preserved for determination. 



* This Journal, vol. xiv. p. 255, September, 1877, 

 \ Ibid, vol. xxi, pp. 422. 423, May, 1881. 

 \ Ibid., vol. xxiii, p. 85, January, 1882. 



