132 EDWARD PHELPS ALLIS jr., 



must be the homologue of the commissural cross bar of my de- 

 scriptions, and not from that cross bar plus a portion of the dorsal 

 section of the postspiracular artery. The blood in this opercular 

 artery is said by Maurer to run, in old embryos, in the opposite 

 direction to that it had in young ones, as it naturally must also in 

 Amia, at a certain period. 



Palais Carnolès Menton, 

 February 10, 1900. 



