1909.] 



Cerebral Cortex of Echidna, etc. 



115 



Fig. 1.— a. Fig. 1.— B. 



Fio. 1. — Diagram of right hemisphere of Echidna, x 2\. A, Lateral aspect ; B, Median 

 aspect. 







Fissures. 





FS 





Sylvii. 





. Fissura antesylvia anterior. 







rhinica posterior. 



//* 



„ frontomarginalis su- 







rhinica anterior. 





perior. 



fpsa 





postsylvia anterior. 



ffi 



„ frontomarginalis in- 



fpspo 





postsylvia posterior 





ferior. 







occipitaKs. 



FH 



„ hippocampi. 



fpspt .... 





postsylvia posterior 



Fvall 



„ vallaris. 







temporalis. 



VC , , , 



, , Anterior (ventral) commissure. 



fasp .... 





antesylvia posterior. 



Dorsal C. 



.. Dorsal commissure. 







A - - - A shows plane 



of Section A. 







£ - - - B 



5» 



B. 







C - - - C 



)) 



c. 







Types of Cortex. 









□ □ □ 





Type I. 







+ + + + . 





Type II. 







X X X X 





Type III. 







0 ® ® (D . 





Type IV. 







o o o o . 





Type V. 



Ziehen's names, thongh clumsy, have the advantage that they remind one 

 of the position of the fissure referred to, and it is for this reason that they 

 are adopted here. 



He takes as his starting point the — 



Fissura Sylvii (FS). — This is generally about 5 mm. in length, and runs 

 almost horizontally backwards. From its anterior end the fissura rhinica 

 anterior runs forwards and the fissura rhinica posterior runs backwards. 



Fissura rhinica anterior (frha) runs horizontally forwards and reaches the 

 mesial surface. Its incision of the mantle edge delimits the olfactory lobe 



