FUNDAMENTAL PLAN OF VERTEBRATE BRAIN 481 
notochord exhibit a similar arrangement. For a more adequate 
comparison on this important point figure 6 of my previous 
paper is here reproduced as figure 5 A while figure 5 B reproduces 
the plan of arrangement of notochord, preaxial and paraxial 
5B 
5 
> 
Fig. 5 Schemas comparing the cephalic portion of the neural plate with the 
underlying notochord-mesoderm relations. 
5 A. (Copied from Kingsbury, ’20, fig. 6). Diagram to illustrate the interpre- 
tation of the cephalic portion of the neural plate. A, region of the retinal area (s); 
B, the region of the olfactory lobes (and cerebrum); C, cephalic end of the 
floor plate (and sutura neurochordalis) ; D, the floor plate; G, primary motor zone; 
H, primary sensory zone; J/7, nucleus of oculomotor nerve; JV, nucleus of tro- 
chlearis nerve. 
5 B. Portrayal of the relations of notochord and mesoderm, as they exist in a 
form in which the head cavities are well developed. JJZ, premandibular somites 
and cavities with their prechordal connection and cross canal; JV, mandibular 
somites and cavities; V7, Hyoid somites and cavities. The lateral mesoderm and 
pericardial cavity are of course related, but not indicated. 
mesoderm essentially as it would exist in any form (e.g., shark, 
turtle, certain birds) in which the ‘head somites’ are well devel- 
oped. To make the comparison more forceful, the cranial nerve 
number marks the somite from which its territory of innervation 
is derived. 
