738 
MR. A. SAWDERS ON THE ANATOMY OF THE 
which was justified when V. Baer (32) discovered that in the course of their develop- 
ment these tuberosities were at first hollow and contained a small tubercle at the 
bottom of their ventricle, which tubercle occupied the position of the corpora striata. 
Of the remaining writers, Hollard (55), evidently unacquainted with the researches 
of Y. Baer, confined the interpretation of these lobes to the region of the insula. 
To conclude the consideration of the cerebral lobes, Miklucho-Maclay (62) and 
Fritsch (66) follow V. Baer ; the former termed the tuberosities in question the 
“ vorderhirn,” and the latter “ hemisphoeria ” or “ stirnhirn.” 
The third pair of tuberosities are the largest bodies in the brain of fishes. They are 
hollow, and consist of the following parts : first, a thin vault of nervous substance, the 
“ tecta loborum opticorum ” of Stieda, which may be termed for shortness “ tectum.” 
These are united together in the mid-line by a transverse commissure, and are closed in 
posteriorly by a tubercle closely attached to the unpaired tuberosity behind. This is the 
“ tuberculam cordiforme ” of Haller, and is more or less developed in different families 
of the Teleostei. 
Along the inner contiguous edges of the tecta a pair of longitudinal ridges of a 
somewhat triangular shape are attached, through the bases of which the before- 
mentioned commissure runs : these form the fornix of Gottsche (34), and the com- 
missure was termed by the same author the “ corpus callosum.” On the floor of the 
ventricle formed by these vault-like structures two hemispherical swellings are placed, 
which being in some fishes of a somewhat curved form, were named by Haller 
“ tori semicirculares.” 
The complicated structure of these tuberosities induced many writers on this 
subject to look upon them as the homologues of the hemispheres of the brain; 
although one would have supposed that the position of the pineal gland and the 
origin from them of the optic nerve would have formed an insuperable objection to 
this interpretation. 
Camper (7) was the first who made any serious attempt to decipher the homologies 
of the brain in fishes. 
These third pair of tuberosities (which for the sake of convenience will be called 
here the optic lobes) were for him the cerebral hemispheres ; the commissure of the 
tecta was the corpus callosum, and the tuberculum cordiforme homologised the corpora 
quadrigemina : an opinion which was also held by Haller ; and the ventricle of the 
optic lobes was the third ventricle. 
Kuhl (21), Somme (24), Cuvier (28), and Leuret (35) followed this interpretation. 
Ebel (9) thought that these lobes, combined with the unpaired ganglion behind 
them, were equivalent to the cerebrum. 
Weber, in his first paper (17), considered that they were the hemispheres, but 
subsequently (22 and 27) lie termed them “ selmervenhugel,” by which he probably 
meant no more than that they were optic lobes, without absolutely homologismg 
them with the thalami optici. 
