200 A RALPH EDWARD SHELDON 
ent nuclei and fiber tracts to these regions in this paper must be 
regarded as provisional, particularly with respect to the centers 
lying within, and immediately dorsal to, the lateral parts of the 
inferior lobes. 
The inferior lobes consist of an unpaired pars medialis, which is 
clearly hypothalamic, and paired partes laterales, the lateral 
lobes, which apparently belong chiefly to the pars ventralis 
thalami. 
The lobi laterales are widely separated rostrally by the inter- 
posed lobus medius, while they meet one another caudal to it. 
Caudally a furrow appears onthe ventral aspect of the lateral lobes, 
the suleus mammillaris of Goldstein (fig. 4). The prominence of 
the lobes mesal to the two sulci, is due to the development dor- 
sally of the corpora mammillaria of Goldstein (fig. 117). Later- 
ally, each inferior lobe shows several lobes and sulci, varying some- 
what in different individuals. Rostrally the great size of the 
nucleus prerotundus and nucleus rotundus causes the development 
of a slight protuberance, appearing on the outside of the lobe (fig. 
3). Further caudally the nucleus cerebellaris hypothalami gives 
rise to a similar enlargement (fig. 3). The lobus medius consists 
of the tuber cinereum rostrally, and the pars infundibularis 
caudally. 
Extending ventro-rostrally from the tuber is found the hypo- 
physis, consisting of the two conspicuous solid lobes, separated by 
a circular constriction; a rostral pars glandularis and a caudal 
pars nervosa. Ventrally these are separated into symmetrical 
parts by a longitudinal median furrow (fig. 4). Extending cau- 
dally from the caudal margin of the pars i.fundibularis of the lobus 
medius is a narrow, thin, glandular, men.branous sac, the saccus 
vasculosus, opening into the infundibular cavity (fig. 4). 
The median cavity of the forebrain extends caudally and ven- 
trally between the two pedunculi thalami and thalamus proper, 
giving rise to diverticula which penetrate the lateral lobes. (For 
a more detailed account of the ventricles of the teleostean infe- 
rior lobes see Goldstein (’05), pp. 189-195, figs. 13-19; Edinger 
(08), fig. 171.) 
