CENTRAL NERVOUS SYSTEM IN VERTEBRATE ANIMALS. 
737 
tuberosities placed in a series from before backwards, and one unpaired tuberosity. 
The homologies of these tuberosities are not yet settled. Miklucho-Maclay (62) 
has within the last few years proposed an arrangement differing considerably from 
that ordinarily received — an arrangement which was endorsed by the great authority 
of Gegenbaur (67) in his ‘ Grundztige der vergleichenden Anatomie,’ to which I 
find that he still adheres in his recently published ‘ Grundriss.’ Notwithstanding 
this, it appears to me that the interpretation adopted by Stieda (58) is more likely 
to be correct, and that author, in a subsequent paper (64), has given a detailed argu- 
ment against their opinion. 
The first pair of the tuberosities in the brain of fishes may be looked upon as the 
homologues of the bulbi olfactorii (fig. 1, ol.). They are pear shaped, and are not (at 
least in Mugil ) connected together by a transverse commissure, but are each united 
separately to the second pair of tuberosities, to the anterior end of which they are 
closely applied. In some species — as, for instance, in the members of the Cod family, 
and others — the lobi olfactorii are not arranged as above mentioned, but are placed 
immediately over the nasal sacs, and are connected to the cerebral lobes by a long 
commissure ; in which case the latter has the appearance of occupying the most 
anterior part of the cranial cavity. 
The second pair of tuberosities, which I will term the cerebral lobes (figs. 1 and 2, ce.), 
are more or less rounded ; they vary in size in different species. In some fishes, such 
as the Basse ( Labrax Lupus) and Scorpcena Porcus, these bodies present furrows and 
ridges on their surface which might be looked upon as rudimentary convolutions. 
They are united by a transverse commissure which is situated on their inferior edge, 
and nearer the posterior than the anterior end. 
Many of the older writers, who having dissected only fishes of the Carp family, in 
which the first pair of tuberosities are situated far in advance of the remainder of the 
brain and outside the cranial cavity, looked upon this second pair as the lobi olfactorii. 
Of these, Haller (4) considered that they subserved the function of smell together 
with the lobi inferiores or hypoaria ; others — as Camper (7), Ebel (9), Weber (17), 
Kuhl (21), Somme (24), Gottsche (34), Mayer (49), and Klaatsch (44) — thought 
that they alone constituted the lobi olfactorii; while Treviranus (13), who at first 
termed them “ Pdechforsatz,” subsequently altered his interpretation, and in accordance 
with a theory which he developed at a later period termed them “ Vordere Hemisphere. ” 
Philipeaux and Vulpian (45) considered that they represented the caruncula mam- 
millaris at the middle root of the olfactory nerve ; but the latter (56) subsequently 
came to the conclusion that they were the hemispheres of the brain. On the other 
hand, Serres (25), Buchner (33), Leuret (35), and Baudelot (61) homologised 
them with the hemispheres of the brain without reserve. Girgensohn (42) was not 
decided, but thought that they might represent the first rudiments of those bodies. 
Tiedemann (15) was the first who compared them to the corpora striata with the 
hemispheres, and their commissure to the antei’ior commissure of the brain — an opinion 
5 b 2 
