1387] The Dipnoan Brain. 547 
af it the double outline indicates the existence of a peculiar, thick, almost etal 
nous, and appar ently non-vascular envelope, the nature and relations of which a 
undetermined. No attempt has been made to show the arachnoid. From what fag 
ven of the region of the optic lobes; the 
diacæle to the larger part of the “third ventricle ;” the au/a, which is com 
confounded with the third ventricle; is really the mesal division of the proso scaler’ or 
irregular cavity of the prosencephal; its other divisions are eg procele (* lateral 
ventricle”) and rhinocele (* olfactory ventricle’) on each s 
Fic. 1. 
ul 
np "solars 
f 3 
ee ae 
X 
$ 
Dr E » . Mey 
P , í end 
| Zeer Be sees: 
a N \ 
Y 
Fic. 1.—Medisection of the brain of No. 425 ine 2). The natural "9 surfaces 
are those of the mesal aspect of the meee! lobe and crus and of the larger part 
of the “cerebral hemisphere.” The supraplex in this specimen is very me com- 
ne r the prerima, through which it finds entrance into the proceeles, as seen 
n Fig 
Bice 2, 
Fic. 2.—Part of the same brain (X z the left prosoccele exposed so as to show 
the extent of the plexus after its entranc e area marked Zora is the lateral 
i of the aula, and is more er called “ foramen of Monro;” hph indi- 
ce 
aes the hypophysis. 
