182 AETHCR WILLEY. 



and such as might well be expected to occur in distantly re- 

 lated forms with such totally different habits of existence, 

 while others are to be accounted for by a wide interpretation 

 of the principle of correlation between structure and function. 

 8. Many difiFerences of detailed structure in the pharyngeal 

 wall and its skeletal supports between the Enteropneusta and 

 Amphioxus are to be correlated with the fact that, in the 

 former, the tongue-bars are larger (often, as in P. flava, very 

 much larger) than the primary bars, while in the latter the 

 reverse condition obtains. 



Additional Note. 



As the Marshall Islands are distant about two thousand 

 miles from New Caledonia, and as the species figured by 

 Eschscholtz renders possible the interpretation that its genital 

 pleura had a more dorsal origin than in the species above 

 described from New Caledonia, it is advisable provisionally 

 to name the latter P. flava-caledoniensis, or simply P. 

 caledoniensis, until the form from the Marshall Islands 

 comes to be re-examined. 



Isle op Pines; 



August 2nd, 1896. 



