442 C. JUDSON HERRICK 



of the thalamus and accompanies the lateral border of the nucleus 

 dorsalis thalami for its entire length. It also overlaps to some 

 extent the pars ventralis thalami (figs. 36 to 39). 



Gaupp in 1899 summarized the most important data upon the 

 structure of the brain of the adult frog in the literature up to 

 that date, together with a wealth of new observations, and his 

 excellent account should be the point of departure for all subse- 

 quent work. I have examined a very large number of brains 

 of different species of frogs prepared by diverse methods, includ- 

 ing those of Weigert, Nissl, Golgi and the silver reduction method 

 of Ram6ny Cajal. The details of my observations must be re- 

 served for later publication and we shall here consider only such 

 general features as have a direct bearing upon the problems 

 of the subdivision of the hemisphere and the morphological rela- 

 tions of these parts. The necessary figures will be found in the 

 works of Gaupp ('99), Kupffer ('06), Kappers ('08), B. Haller ('08), 

 Snessareff ('08) and the brothers Ramon y Cajal. See also fig. 40. 



In the adult frog, as already stated, the fundamental parts of 

 the hemisphere have attained the typical amphibian form. The 

 shape of the hemisphere has considerably changed, as compared 

 with urodeles and larval anurans, especially by the further evagi- 

 nation of structures found in earlier stages in the telencephalon 

 medium, by the consequent contraction of the interventricular 

 foramina and by the relative increase in the dorso-ventral diam- 

 eter of the hemispheres. The lateral ventricles are dilated ver- 

 tically and contracted laterally, thus giving to the cross-section 

 of the hemisphere dorsal and ventral angles which form sharp 

 boundaries between the lateral and medial parts. We shall next 

 review the form and distinguishing characters of the five parts of 

 the cerebral hemisphere of the frog. 



The peculiar fusion of the olfactory bulbs seems to be confined 

 to the bulbs themselves, as in the tadpole, though the participa- 

 tion of a small amount of secondary olfactory tissue (lobus olfac- 

 torius anterior) cannot certainly be excluded. Some fibers in 

 diffuse formation cross the median plane in this region. 



The pars ventro-medialis hemisphaerii (epistriatum, P. Ramon 

 y Cajal; eminentia septalis, Gaupp; pars septalis hemisphaerii, 



