Johnston, Forchrain Vesicle in Vertebrates. 489 



bulbs. These relations have been described and figured by several 

 authors. (See Kappers 190G, 1907, Johnston, 1906, Fig. 151.) 



Jf. Amphibians. 

 In the adult amphibian brain the large size of the telencephalon 

 and the form and relations of its nervous and membraneous portions 

 are of interest for our problems. The large telencephalon has 

 thinner walls and larger lateral ventricles than are found in sela- 

 chians. The lateral ventricles are connected with the median ven- 



X 



/■ wPf"-^^ 



I 

 t ; 



pren. 



m 



' Fig. 23. Fig. 24. 



Fig. 23. Amblystoma punctatum, neural plate stage. Sagittal section of 

 head end. Ectoderm dark, neural plate medium, entoderm light. X 25. 



Fig. 24. Amblystoma p., ueuropore stage. Sagittal section. The section 

 falls to one side of the median plane in the dorsal region and shows the 

 mesoderm lateral to the notochord. Its cephalic limit is the same as that 

 of the notochord. x 25. 



tricles by wide but well defined interventricular foramina (Johns- 

 ton 1906, Fig. 150, 151). The lateral ventricles extend for^vard 

 into the olfactory bulbs and also have a caudal prolongation into the 

 so-called occipital pole of the hemisphere. 



The tela of the diencephalon is separated from the membraneous 

 roof of the telencephalon by a prominent velum transversum which 

 in the adult becomes complexly folded in connection with the chorioid 

 plexus. In front of the velum is a highly developed paraphysis. 



