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AXXALS XEW YORK ACADEMY OF SCIENCES 



primitive clieiropterTgium than is the pectoral of Saiwipterus. Klaatsch 

 (1896) would derive the cheiropterygiiTin of Amphibia from the crossop- 

 terygium of Pohjpterus, but the lack of a single basal piece or humerus, 

 as well as the secondary multiplication of the distal radials, are aberrant 

 specializations. However the pectoral of PoJypterus does suggest the 

 tetrapod type in this respect : that, as Klaatsch and Budgett have shown, 

 it can be turned downward almost like a hand, so that the larval fish 

 sometimes rests on the palmar surface of the dermal rays: the pectoral 



Fig. 6. — Pectoral girdle of Polyptenis bichir 



A, Left side, outer view. B, Posteroventral view. 



Deirmal elements: cv, clavicle; clj, cleithrum ; s.cl, supracleithrum ; po.cl, postcleithrum : 

 p.t, posttemporal. 



Cartilaginous elements: to. coracoid ; se. scapula. 



This modern fish retains the true clavicles of the Devonian crossopterygians and 

 tetrapods. Its scapulocoracoid, however, parallels that of more typical fishes and affords 

 a short, wide base for muscles that raise and lower the fin. The forked posttemporal 

 and wide supracleithrum serve to connect the girdle with the skull ; while the marked 

 concavity of the whole anterior margin of the girdle denotes the presence of a large 

 operculum and large branchial arches. 



is also well provided with muscles for elevating, depressing, protracting, 

 retracting, abducting, adducting and twisting the fin (Klaatsch, Braus). 

 Before considering the relationship of the Ehipidistia to the Tetrapoda 

 it is necessary to decide which is the most primitive family, and what 

 has been the trend of evolution within the group. Smith Woodward 

 (1898, pp. 71-80), perhaps influenced partly by the view that the 

 '•archipterygial" type of fin is primitive, seems to have regarded the 

 Holoptychiidge as having the most primitive paired fins, and the Ehizo- 

 dontidas as more progressive in the ''abbreviation*' of the paired fins. 

 'Through Bliizodopsis and Gyroptychms;' he said (p. TT), "the Ehizo- 



