268 C. JUDSON HERRICK 
in the Anura there followed differentiation of a specific vomero- 
nasal nerve, vomeronasal formation, ventrolateral olfactory 
tract, and amygdala, as these are found in the brain of the frog. 
In the various fishes the relationships of the structures here 
under consideration are exceedingly diverse. In ganoids and 
elasmobranchs the available descriptions do not indicate the 
presence of any differentiated center which can be compared with 
the anuran amygdala with any very definite assurance, though in 
some forms some of the corresponding functional connections 
are present in a less specialized arrangement more nearly 
comparable with that seen in the urodeles, and in sharks the 
differentiation has advanced in a different direction. 
In teleosts the nucleus teniae of the carp as described by 
Sheldon (’12) resembles fairly closely in position and fiber connec- 
tions the anuran amygdala. It receives fibers of the lateral 
olfactory tract and sends fibers to the habenula. The tractus 
pallii (tractus olfacto-hypothalamicus lateralis) reaches the 
adjacent “nucleus pyriformis,” but is not described as entering 
the nucleus teniae. Similar relations are described in other 
teleosts by Goldstein (’05), Kappers (’06, p. 11), and others. 
(The nucleus teniae and tractus teniae of Johnston’s descriptions 
of fishes refer to quite different structures from those so named 
by the authors just mentioned. Johnston, ’11, p. 35.) 
The absence of a differentiated vomeronasal organ in fishes 
raises the question how far these structures can be compared 
with the anuran amygdala. It is probable that the primordial 
elements of the amygdalo-pyriform complex of higher brains 
(and of the hippocampus as well) are here represented in various 
combinations; but that in none of these species are these elements 
combined to form an amygdala of the type seen in the frog, for 
in the absence of the vomeronasal apparatus the integrating 
factor essential in the latter case is lacking. 
Living forms of Amphibia, it is now generally agreed, cannot 
be regarded as ancestral to any Amniota, so that the anuran type 
of amygdala is not necessarily the point of departure for this 
complex as found in‘higher forms. ‘The elements here associated 
may be found dissociated or combined in other patterns in 
