1910.] Manufi of Oudenodon, etc. 439 



is, however, analogous in crrtnin respects with tiic posterior dorsal ^n of the 

 Devonian Cfossopterygian Ilolopfijchius Icptopterus (cf. Woodward, 1898, 

 fig. 19, p. 22). The metacarpals of Enjops are suggestive of the radial 

 cartihiges of the pectoral fins of Pohjptcras; its radius and ulna recall the 

 pro- and ni(>taptervgia of that form; while the mass of carpals might cor- 

 res]xmd with the mesopteryginm. The suggestion is that the proto- 

 Amphibian or Crossopterygian ancestors of the land living vertebrates had 

 paddle-like fins in which the bony elements, arising from the concentration 

 of the basals and radials, became widely extruded from th(> body wall. Be 

 that as it may, the manus of Erijops, as fully shown Ijy Broom, certainly 

 foreshadows the type seen in the Anomodonts. 



The most striking feature of the manus of Oudenodon (Fig. 28, no. 2) is the 

 retention of a more or less paddle-like character. The metacarpals are very 

 short, much as in Eri/ops, and all the carpal elements of that genus are 

 represented. In comparison with the carpus of mammals, that of Oudenodon 

 retains two elements which are never found free in mammals, namely, the 

 second centrale (c-) and the fifth distal carpale. The manus of the Endo- 

 thiodont genus pisfhoctcnodon (no. 3) retains the so called "])ra^pollex" 

 which seems to persist in the embryo Didelphis (no. 9) and in certain 

 Insectivores and Ivodents. The importance of this structure has been 

 emphasized by Bardeleben (1889). Whether it be called a digit or not is of 

 little moment; its presence in the Permian Anomodonts and in certain 

 modern orders is the important point. Moreover, as regards its status as a 

 digit, there is no convincing evidence that it was not present in the Amphi- 

 bian ancestors of the Anomodonts. The four fingered Branchiosaurus 

 and the five fingered Keraterpeton probably do not stand very near to the 

 direct ancestors of the Anomodontia. The prsepollex is, however, not known 

 in Eryops nor in the Dromasaurian Galechirus, but it is figured in the 

 Therocephalian (?) Theriodesmiis (Fig. 28, no. 5). As observed by Broom 

 (op. cit.) the manus of Galechirus (no. 4) compares on the one hand with that 

 of such typical reptiles as Sphenodon and on the other with that of TJierio- 

 desmus. The manus of Thcriodesmus, which is possibly a Therocejihalian, 

 as reconstructed by Bardeleben and Broom (Fig. 28, no. 5), shows a decided 

 progress toward the mammalian type, when compared with that of Oudeno- 

 don. The metacarpals are more slender and the oblique arrangement of the 

 carpus is replaced by a more horizontal arrangement, betokening perhaps a 

 more advanced pronation of the manus and better rimning powers. The 

 radiale, intermediiun, ulnare and pisiform distinctly foreshadow the scaph- 

 oid, lunar, cuneiform and ])isiform respectively of mammals. The second 

 centrale is reduced in size, the fifth distal cari)ale is apparently absent, and 

 the fourth which is enlarged and, like its homologue the unciform of mam- 



