xx Proceedings. \_April 13th, 1915. 



Bowie (Special Publication, No. 22)(zj.to, Washington, 1914), 

 presented by the United States Coast and Geodetic Survey, 

 Washington. 



Mr. Henry Day, B.Sc, read a paper entitled " Some 

 points bearing on the Relationship of the Fishes and 

 the Amphibia." 



The paper deals with the three specimens of the so-called 

 parasphenoid bone in Rhadinichthys monensis from the Man- 

 chester Museum collection. 



The three specimens together give an excellent idea of both 

 dorsal and ventral surfaces of the bone so that an accurate 

 description can be given, thus providing material for a deter- 

 mination of the relations and homology of this bone in the 

 Crossopterygian fishes, and in the primitive Amphibia and 

 Reptilia. It was shown that in all these groups the bone is 

 really compound, consisting of parasphenoid and basisphenoid 

 combined, and also that the bone is remarkably constant in its 

 form and relations. 



The remarkable constancy in form was contrasted with the 

 entirely different form of parasphenoid which prevails in fossil 

 and living Dipnoi, and was brought forward as a strong argu- 

 ment in favour of a development of the Tetrapoda from a 

 Crossopterygian Ganoid stock rather than from the Dipnoi. 

 Further, it was pointed out that in all cases this bone takes 

 part in the suspension of the upper jaw, a process of the 

 metapterygoid region of the palato-quadrate uniting with the 

 basipterygoid process of the basisphenoid region of this com- 

 pound para-basi-sphenoid bone. This "pedicular" connection 

 thus constitutes a form of autostyly common to the Crosso- 

 pterygii and the primitive Amphibia and Reptilia but totally 

 different from the autostyly found in Dipnoi, which latter type 

 is never found in the Tetrapoda. Hence the common pedicular 

 autostyly forms another argument in favour of a Crossopterygian 

 derivation of the Tetrapoda as opposed to the Dipnoian deri- 

 vation. 



