GREGORY, PRESENT STATUS OF ORIGIN OF TETRAPODA 



359 



latter; he called attention to the resemhlances in the teeth between 

 Sauripterus and Bluzodopsis and put forth the hypothesis that the 

 cheiropterygiiim had been evolved from the preaxial part of a pre- 

 Sauripterus fin. Later in the same year (1913) Dr. Broom published 

 in the Anatomisch er Anzeigcr a partial restoration of the shonlder-girdle 



•^^==^r\. 





Fig. 8. — Right pectoral limb of Eusthetiopteroii foordi. After Fatten 



A Carboniferous rhizodont rhipidistian. 



The broad ascending blade is the cleithrum ; the single proximal piece was compared 

 by Professor Patten with the tetrapod humerus, the next two elements with the radius 

 and ulna, and the more distal elements with the carpus and digits, respectively. 



The single proximal piece (humerus) probably represents the mesopterygium of sharks : 

 together with the central line of pieces it appears to be homologous with the mesaxial 

 series in Ceratodvs ; the divergent rods above and below this axis represent the pre- and 

 post-axial radials, respectively. The lower main branch is the meta pterygium. 



and bones of the pectoral paddle of Sauripterus together with a sketch 

 of the back part of the jaw. 



With the view of testing my first idea that the ascending blade of the 

 Sauripterus shonlder-girdle is the homologue of the scapula of tetrapods 

 notwithstanding its dermal origin, I have studied the pectoral limb in 

 various fossil and recent fishes and amphibians. Through the kindness 

 of Mr. Grimshaw of the Royal Scottish Museum of Edinburgh I was 



