326 ELIZABETH CAROLINE CROSBY 
Commissures oluhestorebraine-s)- eee ee eee eee ee eee ee 365 
Commissura hippocampl............... ected hin i, od A AE ie ap eA Ee aa 365 
Gommissuraranterior..4c sae eee: Oe ee eee 366 
Tractiolsae diagonal bandiof:Brocatan... 0s: eee aes ce eee er 366 
SErtacbemmarmaligeys «sic. sewer aot Rees Mee ec Re ee OT 367 
‘ ‘Lheycommissural portionis..9-62 6-6 eee ee Ee eee eee 367 
aRHEypreo pele, POLblOM waste eco re tn Eo eee 367 
PANS CUS soiree ace else be eee oe eee EEE oe ee 368 
EY Coc Ove) ts pena I Anon ARP ub i 06 Ton am ule in ine Melgar eer Cie be 368 
Hibraetangentialess-<.ccnd cise eee ee ee ee ae ne 368 
1 OY0Y i 01S, Cee Cera es bea i), ER RE eI a CNR IR Wee Rm: ORE Very ate ra) Bs | 369 
Colummayforniciss2 cease Ce ee ee ras en ee ee 369 
POrDIXA ON GUS scr. rp.< se oor ho eo Ne os en ee 369 
Stria ime dulllanis: 3c. sh cs eee oo eee ee eee ae Se ee 370 
‘iraActusicortico-nabenularis medialis: 4b eee ALE ee eee 370 
Tractus cortico-habenularis lateralis anterior....................... 370 
Fractus cortico-habenularis lateralis posterior...................... 372 
tractus olfacto-habenulanigimedialistes. ss 54-0 pees nee nee 372 
iractusomacto-habeniulanisilatenclisues sere eee eee eee 372 
fractus olfacto-habenularis posterior... 2.00240... sees) cece oe 373 
Olfactory proyection+tracts, 2. tc a eee 373 
Ventral olfactory projection tract. fossa) hse oe a eee 373 
@lisetory prorection tractiol Cajal sto es Sate ee ee ee 373 
Basalkforebrain: bundles rs. 4 1h een eR ee pe tae Ae a 374 
Miediralitionebrainybundlless se eee eae ene ee eee 374 
wateralvforebrainibundlev sm an.ceeetis® stone a eee 375 
General-dis cussion 4s) )o ke tee ee oe eee te ied te ee ee 375 
Sinmniivary: 504 Aer Ne. Pee he OT eae cA et Pet ie eRe eee 384 
The olfactory system is highly developed in the reptilian fore- 
brain. Not only are large basal nuclei present, but there is 
clearly differentiated cortex and all the important olfactory 
tracts of higher forms are represented. The larger part of the 
forebrain, then, is concerned in the reception of olfactory im- 
pulses and their correlation with incoming diencephalic impulses 
of various sorts. In fact, the diverse distribution of the incom- 
ing diencephalic tracts, each of which has its own characteris- 
tic functional significance, has been one of the prime factors 
in the differentiation of the forebrain into its various cortical 
and basal centers. Although the greater part of the reptilian 
forebrain is under the influence of the olfactory fibers, there is 
a considerable portion which receives a much smaller number 
of these fibers and is dominated by the ascending fibers from 
the somatic nuclei of the thalamus. Through these somatic 
