THE DIENCEPHALIC FLOOR 219 
5. The post-infundibular eminence, a small irregular and 
median protuberance in front of the corpora mammillaria and 
caudad to the infundibular bulb. 
6. The mammuillary bodies. 
7. The lateral eminences, a pair of bilateral protuberances 
situated one cn either side of the post-chiasmatic eminence. 
Of these structures the post-chiasmatic, post-infundibular and 
lateral eminences constitute the tuber cinereum, while the in- 
fundibular process is appended to the tuber by the infundibular 
stem. In an earlier paper (8) the writer so interpreted the text 
and figures published by Retzius (9) as to assign the term emi- 
nentia saccularis to the post-chiasmatic eminence. Upon further 
investigation, however, it became obvious that Retzius referred 
to what is here called the post-infundibular eminence. 
In the attempt to estimate the homological values of the 
structures in this region of the brain, serial sections obtained 
from the following adult forms were studied: . 
Squalus acanthias Lepus sylvaticus Canis latrans 
Mustelus laevis _ Sphingurus prehensilis Canis familiaris 
Lepidosteus osseus Mephitis mephitica Genetta vulgaris 
Rana pipiens Odocoelus hemionus Felis domesticus 
Menobranchus Odocoelus virginianus Felis pardus 
Iguana tuberculata Oryx beatrix Felis leo 
Gallus gallus Ovis tragelaphus Lemur macaco 
Botaurus lentiginosus Ovis aries Macacus cynomolgus 
Didelphys quica Castor canadensis Nyctipithecus trivirgatus 
Bradypus tridactylus Mirounga (Macrorhinus Babuin cynocephalus 
Dipus aegypticus angustirostris) Hylobates hoolock 
Dasyprocta agouti Nasua narica Simia satyrus 
Mus decumanus Ursus horribilis ' Homo 
Studies of this portion of the neuraxis in the gross, even with 
the aid of the binocular, are quite unsatisfactory because of the 
compact arrangement of the structures which must be examined, 
and. because dissection in this region can scarcely be performed 
without seriously disturbing the relation of the parts. For this 
reason, the Born method of reconstruction was employed in the 
study of the adult cat, dog, rat, rabbit, opossum, common fowl and 
dog-fish. It was also used in the reconstruction of models which — 
demonstrate the ontogeny of the diencephalic structures in the 
cat, chick and dog-fish. 
