184 
not but be struck with the inappropriateness of Broca’s limitation 
of the limbic lobe (4). Thus Schafer says (34, p. 155) :—‘ The 
callosal gyrus, with its continuation the hippocampal gyrus, were 
separated by Broca, on morphological grounds, from the other 
parts of the hemisphere, as a distinct lobe, intimately united in 
front and below with the olfactory lobe ; and the name of grande 
lobe limbique was given by him to these combined lobes. To this 
lobe of Broca, Schwalbe added the other central parts of the 
mesial wall of the hemisphere, viz., the lamina septi pellucidi and 
the dentate convolution, as well as the fornix; . . . naming 
the whole lobe thus reconstituted the ‘falciform lobe,” the 
olfactory lobe being, however, excluded.” In this modified form 
Broca’s idea is generally accepted to-day, as the above quotation 
from a recent standard text-book shows.* Yet, what grounds 
had Broca for this definition of his lobe? As the result of an 
examination of a series of Mammalian brains, he came to the 
conclusion that the different parts of this lobe, “qui peut donc 
étre comparé a une raquette dont l’anneau entourant le seuil de 
Vhémispheére,” was intimately connected with the olfactory bulb. 
The callosal gyrus, however, is not connected with the olfactory 
lobe, and the only relation which it has with the rhinencephalon 
is by means of associating fibres, such as proceed also to other 
parts of the pallium. The callosal gyrus therefore, from the 
histological and comparative standpoint, has no more right to be 
considered as part of the limbic lobe than any other part of the 
pallium. Again, a glance at the cerebrum of WVotoryctes shows 
that the “limbic lobe” of Broca is.not “limbic,” since it does 
not form the border of the hilus. The true limbic lobe (which is 
also undoubtedly associated with the olfactory) is formed of a 
morphological dorsal limb—the hippocampus, and a ventral—the 
pyriform lobe meeting behind (vide 36, fig. 1), where the latter 
overlaps the former ; and united in front by the precomimissural 
area and tuberculum olfactorium. In Wotoryctes (fig. 3) the true 
upper limb of this lobe forms not only the upper, but also the 
posterior, and part of the inferior, arcs, the pyriform forming the 
anterior part of the inferior arc. The limbic lobe, as thus 
defined, corresponds to Turner’s “‘ rhinencephalon.” In Eutheria 
where the dorsal—horizontal—limb of the hippocampus disap- 
pears, the rudiment of that structure—the indusewm griseum ot 
Obersteiner (gyrus supracallosus and gyrus geniculi of Zucker- 
kandl (43) including the strie Lancisi1)—represents the dorsal 
limb, with the gyrus subcallosus of Zuckerkandl, and locus 
perforatus anticus as anterior connections. 
* Note.—Debierre (6) has recently questioned the propriety of including 
the callosal gyrus in the falciform lobe (as also has Edinger, 8), and came 
to the same conclusion as that arrived at here, though working from a 
different standpoint. 
