C. Judson Herrick 



The functional connections of this área have been described by Shel- 

 don. In the carp the central core of the telencephalic thickening contains 



large neurons of very characterictic form, 

 though these are mingled with other types ot 

 cells and this área has no clearly defined boun- 

 daries. Fibers of the tractus olfactorius termí- 

 nate within it, and this defines it as part of the 

 área olfactoria and not a true corpus striatum. 

 It receives short correlating fibers from the área 

 olfactoria medialis and in Osmerus (Holmgren) 

 also from the área lateralis. The most charac- 

 teristic feature of this área is the tract of ascen- 



21 



Fig. 21. — Diagrammatic 



transverse section through 



the telencephalon médium d'mg «somatic sensory connections from the 



of Amia taken immedia- ,c-, ^■, ^ u cu i • 



thalamus> (Sheldon), whose fibers end m sy- 



tely in front of the commis- 

 sura anterior, illustrating 

 the arrangement of the 

 subdivisions of the área ol- 

 factoria. From a speci- 

 men 25 mm. long. 



naptic unión with the large neurons already 

 mentioned. The axons of these neurons des- 

 cend into the ventral part of the thalamus. 

 These ascending and descending fibers are the 

 forerunners of the true tractus strio-thalamicus, an important component 

 of the lateral forebrain bundle of higher brains. This, then, is an olfacto- 

 striatal correlation center of the same type as 

 that which I have described (192 1 a) in the la- 

 teral wall of the urodele cerebral hemisphere. 

 (It should be mentioned that the presence in 

 teleosts of these ascending fibers and also ot 

 those of the tractus pallii mentioned in a prece- 

 ding paragraph is questioned by Holmgren.) 



5. Área somática. — In Amia, as in Acipen- 

 ser and Acanthias, this extends directly back- 

 ward from the área olfactoria lateralis and área 

 olfacto-somatica into continuity with the non- 

 olfactory somatic región of the thalamus (figu- 

 res 21, 22). It is of the same physiological 

 type as the thalamus. The área somática of 

 Amia receives fibers from the optic and somes- 



thetic región of the thalamus (tractus thalamo-corticalis of Johnston, 

 191 1 aj and discharges into the ventral part of the thalamus by the so- 



22 



Fig. 22. — From the same 

 specimen as the last taken 

 immediately behind the 

 commissura anterior. Fi- 

 gures 21 and 22 are mo- 

 dified from Johnston's fi- 

 sures. 



