i68 C. Judson Herrick 



nucleus taeniae of Sheldon (1912), and most of the primordium pallii of 

 Holmgren (19201. In the higher Teleostomi, as compared with Acipen- 

 ser, this área is greatly enlarged, everted laterally and internally more 

 complex. l^here is great diversity in different species, but in no case has 

 the differentiation advanced far in the direction of truc cortical structure 

 as this is seen in higher vertebrates. It is obscurely divisible into three 

 parts which are here termed dorso-medial, dorso-lateral, and lateral parts 

 of the área dorsalis (figs. 23, 24). These parts differ in internal structure, 

 and their limits are not clearly defined. In many species these parts are 

 separated by more or less clearly defined ventricular sulci. Their syno- 

 nomy is expressed approximately in the accompanying table, though the 

 limits of the parts as defined by various authors are not exactly the same. 

 Holmgren, for instance, includes in his «^ general pallium» also the área 

 olfacto-somatica of my analysis (see beyondi. 



pars dorso-medialis nucleus olfactorius lobus pyriformis I epistiiatum 

 dorsalis I 



(primordium hippocampi)! 



pars dorso-lateralis nucleus olfactorius general pallium área olfactoria late- 

 lateralis | ralis 



pars lateralis Inucleus olfactoriusiprimordium hippo- nucleus taeniae 

 lateralis campi 



(lobus pyriformis and nu- 

 cleus taeniae i 



AU parts of the área olfactoria dorsalis receive fibers of the tractus 

 olfactorius and all discharge fibers into the hypothalamus. The dorso- 

 medial part receives fibers from the área olfactoria lateralis and discharges 

 fibers into the área olfactoria medialis. Probably there are correlation 

 fibers running in the reverse direction in both cases, though these have 

 not been observed. The dorso-lateral part is in very intímate functional 

 relation with the underlying área olfacto-somatica and these are by some 

 authors regarded as a single región. The lateral part is the only subdi- 

 visión of the área jlfactoria dorsalis which sends fibers to the habenula. 

 Ascending hypothalamic fibers of the tractus pallii termínate in the lateral 

 and dorso-lateral parts, but do not seem to reach dorso-medial part. 



3. x4rea olfactoria lateralis. — In Amia this is a relatívely small región 

 on the ventro-lateral aspect between the bulbus olfactorius and the com- 



