1 86 C. Judson Herrick 



hippocampal cortex; it may, therefore, be called primordium hippocampi. 

 This is in agreement with Johnston's main thesis, though we cannot ac- 

 cept all of the arguments which he brings in support of it. 



Cortical primordia in fisJies. — Nothing structurally resembling the ce- 

 rebral cortex of the Amniota has been described in the brains of any 

 adult fishes except the Dipnoi (Lepidosiren, ElHot Smith, 1 908; Protop- 



p f>'P 



9 P 



-bol. 



nuc. ol. m. 



29 



Fig. 29. — Acanthias 5 cm. long. Transverse section through the forebrain at 

 the level of the olfactory bulb, illustrating Holmgren's observations on the histo- 

 genesis of the walls of the telencephalon. In the área olfactoria dorsalis there 

 are three regions of cellular proliferation which he designates hippocampal 

 pallium [p. Iiip.), general pallium (g. p.). and pyriform pallium (p. p.). Redrawn 

 from Holmgren (1922, fig. 15). 



terus, Holmgren, I922j, though numerous authors have given to diíTerent 

 regions ñames implying cortical homologies — archipallium, palaeopal- 

 lium, primordium hippocampi, etc. 



Sterzi (1912, pp. 1210-1217) gives a brief general description of the 

 histogenesis of the walls of the lateral lobes of Acanthias and describes 

 the formation of áreas of superficial gray matter which he calis palaeo- 

 pallium. 



Very recently Holmgren (1922) ^ has reexamined the development of 



' A brief summary of this paper has been published by Gertie Soderberg, 

 Acia Zoológica, Bd. 3, 1922, p. 75. 



