334 AXXALS XEW YORK ACADEMY OF SCIEXCES 



Although the chondrocranium of Ehipidistia, except for the basioc- 

 cipital and hasisphenoid elements, is not well known, it was probably 

 fnndamentallY similar to that of Polypierus, and here it may be remarked 

 also that the sphenethmoid of that fish is similar to the element of the 

 same name in modern Amphibia, and that Broom (1913, p. 58 T ) ha^ 

 recently described the sphenethmoid of the stegocephalian genus Eryops 

 as recalling that of Polypierus in certain details. 



The lower jaw of Ehipidistia differs considerably in form from that 

 of Stegocephali and retains a full series of gular elements median, paired 

 and lateral, as well as a row of infradentaries : certain of these elements, 

 especially the paired gulars, seem to have been lost in the Stegocephali, 

 while some others are with difficulty traceable. 



In spite of these differences, however, the primitive stegocephalian jaw, 

 as described for instance by "Williston (1913). Broom (1913, p. 5T5) and 

 Watson (1912, p. 11), has many important characters in common with 

 the jaws of Osteolepis and Rliizodopsis, as described respectively by 

 Pander, Traquair and others. Putting together the suggestions of ho- 

 mologies made by Smith Woodward. Watson and Broom (1913, pp. TT- 

 78) we would have the following table: 



RHIPIDISTIA STEGOCEPHALI 



Fir:^t infra dentary Splenial (^Woodward) 



Intermediate infradentaries Postsplenial (Watson) 



Posterior two infradentaries Angular and siiran<riilar 



Dentary Dentary 



Coronoids (? "splenial" of Amia Coronoid and preeoionoid 



and Poli/ptenis) 



Prearticular (f?aunpt€rus) Preartlcular 



Articular Articular 



STEGOCEPHALI 



When the classification of the dermal elements of the skull-roof which 

 has been worked out in the preceding pages for the Ehipidistia is applied 

 to the skull-roof of the Stegocephali the following correspondence results 

 (cf. Fig. 3) : 



