THE CELL MASSES IN THE FOREBRAIN OF THE 
TURTLE, CISTUDO CAROLINA! 
J. B. JOHNSTON 
University of Minnesota 
SIXTY FIGURES 
In continuation of work upon the forebrain, it is the writer’s 
intention to study the origin, growth and differentiation of the 
general pallium in the series of vertebrates. In doing this it 
will bé necessary to keep constantly in mind the relations of the 
general pallium to the hippocampal formation, which has been 
described in earlier papers. The history of the amygdaloid 
complex and of the pyriform lobe is also intimately concerned. 
Finally, the position and arrangement of the fiber tracts connect- 
ing the hemispheres with the brain stem bear an important re- 
lation to the morphology of the cell masses in the forebrain. 
In order to be able to compare given brain structures in lower 
and higher vertebrates it is necessary to have a description of 
the brain of some intermediate form in which the more common 
ichthyopsid characters can be recognized and in which at the 
same time the hippocampus and general pallium are present. 
For this purpose the brain of the turtle has been chosen and it 
serves admirably because of the relationship of the chelonia to 
the ancestors of mammals. The present paper will be con- 
fined almost wholly to description, the review of literature and 
the discussion of hypotheses being deferred to later papers. 
METHODS 
The results here presented have been obtained chiefly from the 
study of cell preparations. The results from the study of fiber 
tracts, although used in connection with this work, will be re- 
ported only briefly. The object has been to define the aggre- 
! Neurological Studies, University of Minnesota, No. 21, July 20, 1915. 
393 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 25, No. 5 
OCTOBER, 1915 
