On the larval development of Amia calva. 



655 



about the same time in fact as in the sea-bass (H. V. Wilson) ; it is 

 Wide and slit-like at first, and becomes gradually pit-like and rounded. 



Figs. A — F. Transverse seetions of gut of larval Amia showing early conditions of 

 the swim-bladder. Figs. A, B, C, Larva of about the tenth day sectioned through the 

 opercula and through the anterior and posterior margins of the pectoral fins. Figs. D, 

 E, F, Larva of about the twenty-second day, sectioned through corresponding planes. 



■A Air bladder, G gut. 



At no time does it add evidence to the view that the mouth is of 

 gill-slit origin^); nor does it show any traces of median asymmetry. 



1) Cf. WiiiLEY, Amphioxus and tlie Ancestry of the Vertebrates, 

 p. 281, summarizing the results of Dohrn, Clapp and H. B. Pollaed. 



