40 AMERICAN PERMIAN VERTEBRATES 



natural relations as one could wish, and they will be so retained in 

 the prepared skeleton. The block containing the distal carpals 

 and the digital bones had been separated in collection from that 

 containing the forearm and proximal carpals, and was not accu- 

 rately readjusted. The three carpal nodules are quite as in the 

 other hand with no traces of others; from which facts I have no 

 doubt that they were the only ones ossified, and they but imper- 

 fectly. Of the digits the bones of the three middle toes were all 

 in perfect articulation save the ungual phalanges of the second and 

 fourth digits, which are missing. Of the first digit, the ungual 

 phalange is displaced and the phalanges of the fifth have not been 

 adjusted to the metatarsal. However, these digits were preserved 

 in perfect articulation in the right foot. From these facts, which 

 I have given in detail because of their importance, it is certain 

 that the phalangeal formula is, as is seen, 2, 3, 4, 5, 3, fixing for 

 the first time the foot structure in an American cotylosaurian, and 

 save for Procolophon, in any member of the order. My figure was 

 made by simply tracing the outlines of the various bones as they 

 He in position and transferring them. The only doubt that 

 remains is the precise width of the space I have left for the carpal 

 elements; it may be a trifle too broad. As is seen, the foot is 

 remarkably broad and flat, lying in the matrix in nearly one 

 plane, with the phalanges short, the ungual ones broad and hoof- 

 like as in Diadectes, and probably also Eryops. The foot 

 resembles that of Diadectes somewhat, save that the proximal 

 carpal bones are large, and the distal row seems to be fully ossified 

 in that genus. 



Three years ago I expressed the opinion that the phalangeal 

 formula 2, 3, 4, 5, 3 (4) was the primitive one for land reptiles, if 

 not for land vertebrates, as observed in Eosauravus copei. Broom 

 is of the opinion that this is the formula in Pro pappus and he has 

 proven it to be that of Procolophon. Dromopus agilis Marsh, as 

 figured by the author and Matthew, shows a similar phalangeal 

 formula. These footprints are from near the upper part of the 

 coal measures in the vicinity of Osage, Kansas. Marsh thought 

 that they were made by a lacertilian rather than an amphibian, 

 a natural error considering the lacertilian form of the prints. 



