Cope.] zlU [April 15, 



The fragment of jaw measures : M. 



Depth at last tooth 040 



Length, including three teeth 027 



Nothing can yet be determined as to the characters of the vertebra? of 



this form. 



2. Ttpothorax coccinarum Cope. U. S. G. G. Survey W. of 100th Me- 

 ridian, Capt. G. M. "Wheeler, 1877, iv, Pt. ii, p. 30. PI. xxii, figs. 

 4, 5 and 9. American Naturalist, 1887, p. 468. 



The genus Typothorax was distinguished by me, 1. c, from Belodon, 

 on account of the regularly pitted surface of the dermal bones. With 

 such dermal bones others of a different character were found, which it 

 was thought best to refer to the same genus, and a fragment of maxillary 

 bone found near by was included in the description. I now suspect that 

 the dermal bones which do not possess the pitted character belong to 

 some other reptile, and the fragment of jaw is not to be referred, certainly, 

 to the TypotJiorax coccinarum, but is more likely a part of a Belodont 

 Saurian. 



The additional material belonging to this geuus and species which I 

 possess consists of two ribs with corresponding dermal bones attached to 

 their superior surfaces, and two femora, one of which adheres to one of 

 the ribs. Also several other more or less incomplete dermal bones. There 

 are numerous other bones accompanying, but their reference is not cer- 

 tain. 



Char. Gen. The peculiarities of this genus as displayed by these speci- 

 mens are as follows : Ribs greatly expanded but with free margins, each 

 overlaid by a band-like dermal bone for its entire length. The dermal 

 bones with pitted sculpture and straight, simple margins, the one acute 

 and the other obtuse. The margins of the ribs are similar to each otherl 

 It results that a gaping groove is formed between the parallel acute edge 

 of the dermal plate and the rib into which the appressed edges of the 

 adjacent rib and plate enter and fit. Thus is formed a complete cuirass 

 covering the body. Femur sigmoid, without distinct head or trochanters, 

 excepting a prominent, ridge-like third trochanter on the posterior face. 

 Condyles with a posterior lobe separated from the external lobe by a fossa. 



It is possible that one of the ribs described is abdominal in position, as 

 it does not appear to have had a head. There is no head preserved on 

 the other. The dermal bands described may be therefore abdominal. The 

 ribs are, however, strongly curved in the longitudinal direction, and it is 

 to be supposed on this account that they are dorsal, and perhaps in the 

 position of flying ribs. The adhesion of a femur to one of them indicates 

 posterior position. The character of the femur is different from that of 

 the BelodontidfB in its trilobate condyles, approaching thus the Goniopod 

 Dinosauria. The third trochanter is much better developed than in any 

 known Belodont.* 

 * Von Meyer Paleeontographica, vii, 1861. 



