6 
similar proliferating areas within the axial lobe. In as much as the 
cortex is largely lost or reduced in birds, the substitution is all the 
more important, and Mr. TURNER has shown that in some cases cell 
clustres physiologically and morphologically cortical have buried them- 
selves in the axial lobe in complete independence of the structures 
proper to the latter. 
' ’ = A Fyramıdal 
2 Buandte 
Fig. 1. Part of a longitudinal horizontal section through the brain of the Drum, 
Haploidonotus. The figure illustrates the segregation of cells of different sorts 
in distinet areas. 
In my own study of reptiles I have encountered much additional 
evidence that the principle enunciated is a correct one. It was, there- 
fore, with great interest that the attempt was made to discover the 
fate of the cell masses physiologically equivalent to the cortex cells 
of higher vertebrates. 
In a paper above referred to the writer, in conjunction with 
Mr. C. Jupson Herrick, has shown that the fish cerebrum is marked 
by a rather constant set of fissures, which nevertheless are, with two 
exceptions, not homologous with the fissures of higher brains but 
mark off histologically distinct territories in the axial lobe. There 
is a well-marked rhinalis fissure and a sylvian fissure which is appar- 
ently partly homologous with the flexure or fissure so named in 
mammals because it marks a line of frontal flexure of the entire 
cerebrum. 
The axial lobe is divided by these fissures and corresponding 
