THE ENCEPHALIC EVAGINATIONS IN GANOIDS. 

 By B. F. Kingsbury, 



Ithaca, N. V. 

 [IVith Plate VL) 



The great interest attaching to the extent and interpreta- 

 tion of the membranous roof of the vertebrate brain cephalad 

 of the postcommissure, and the number and significance of the 

 outgrowths occurring in this region may serve as an excuse for 

 the isolated publication of a few facts upon the latter in Ganoids, 

 especially since the presentation of the results of a more gen- 

 eral study of the ganoid brain seems somewhat remote. 



The new and important points are two: (i) the presence 

 in the adult Amia of the first epiphysial vesicle of Hill and its 

 innervation from the left habena ; and (2) the existence in Amia 

 and Lcpidosteiis of lateral cephalic and caudal extensions of the 

 cavity caudad of the velum transversum of Kupffer, constituting 

 considerable diverticula. More emphasis it is felt should be 

 laid on the existetice of the " dorsal sack " and the presence of 

 the paraphysis as distinct structures. A word may be added 

 upon the metaplexus in Lepidosteus which presents some inter- 

 esting features in connection with the diverticula from the 

 diatela. 



Epiphysis. Great interest has always attached to this struc- 

 ture, so constant in the vertebrate series, as the remnant in a 

 greater or less degree of preservation, of a sense-organ once of 

 importance in vertebrate ancestors. Recently fresh interest has 

 been added by the studies of numerous observers which go 

 strongly to show (though not conclusively as yet, it is felt) the 

 presence of two, or possibly more, evaginations from this re- 

 gion of the brain roof. By Hill, Studnicka, and Locy is enter- 

 tained the view that it is the more caudal of these, the epiphy- 

 sis proper, which is most developed in the lamprey and persists 



