4")L > C. JUDSON HERRICK 



fibrous connections. Further consideration of these brains will 

 be reserved pending the appearance of a paper on the subject 

 now in press by Professor Johnston. 



Some considerations regarding the brains of cyclostomes will 

 be found in the discussion on page 470. 



REPTILIA 



The reptilian cerebral hemisphere is characterized chiefly by 

 the highly developed corpus striatum complex and by the presence 

 of true cortex in the pallium. This cortex is arranged in three 

 distinct laminae (cf. fig. 61), the lateral cortex (paleocortex of 

 Kappers, 'OS), the dorsal cortex (cortex ammonis, Kappers) and 

 the dorso-medial cortex (fascia dentata, Kappers). The dorsal 

 and dorso-medial cortex both extend to the extreme rostral end 

 of the hemisphere, the latter here resting directly upon the under- 

 lying secondary olfactory center of the olfactory crus. This 

 condition is repeated exactly in the lower mammals in relations 

 which permit us to homologize the dorso-medial cortex of the 

 lizard without question as cortex hippocampi. Comparison with 

 the adult frog shows that there too the dorso-medial part of the 

 hemisphere extends forward in the same way to the olfactory 

 bulb over the pars ventro-medialis, a fact which justifies us in 

 calling the pars dorso-medialis of the frog primordium hippocampi 

 for its entire length. 



The reptilian septum is further differentiated as compared with 

 the Amphibia, and is in fact similar to that of lower mammals. 

 The unitary collection of cells in its dorsal part which in Amphibia 

 was termed nucleus medianus septi, or precommissural body, is 

 here subdivided into several nuclei. The term precommissural 

 body may be retained for all of these nuclei related to the amphib- 

 ian body of the same name, including the reptilian bed nuclei 

 for the commissures in the lamina terminalis (and the nucleus 

 of the commissura pallii posterior of lizards), though it must be 

 borne in mind that the term is used here in a more restricted 

 sense than by Elliot Smith. That author's pre-commissural or 

 paratenuinal body of reptiles includes also the vestigial primor- 



