CENTRAL NERVOUS SYSTEM IN VERTEBRATE ANIMALS. 
935 
Gottscbe,* who gave them that appellation without any reference to the part of the 
same name in the Mammalian brain; but it seems that the other term, tori longi- 
tudinales, is more appropriate; the former term seems to indicate a theory; but 
Fritsch,. although he uses the latter name, really considers that the bodies in question 
homologise with the fornix of the human subject; this I hope to prove in the end is 
not the case, and thus the term fornix is a misnomer, as having been applied to a 
different structure. These objections do not apply to the name tori longitudinales, 
which involves no sort of consideration as to theory, but simply states a fact of form. 
Tori Semicirculares. 
The tecta lobi optici having changed their position, and having been relegated to the 
inferior surface of the brain, while the tori semicirculares have retained theirs without 
displacement, the relative position of these two parts comes to be that of the egg to 
the egg-cup, or, as Ecker puts it, that of an oyster to its shell. The torus semi- 
circularis forms a tuberosity of rounded form, bounded below and on the outside by 
the tectum. It may be divided into two parts, easily distinguishable from each 
other, the upper part consisting principally of nerve cells and fibrillae dispersed in a 
granular neuroglia. The lower part on which it rests contains more nerve fibres, which 
belong to the system of the commissura ansulata. 
The upper part differs in structure from the corresponding part in M. cephalus and 
Labrax lupus in the same diffused way as the tectum. The small cells which do not 
show such elongated processes as in the species just cited, are scattered irregularly 
among the fibrillse which traverse this body in all directions through the upper section 
of the tuberosity. They measure from about 0*005 millim. to 0*0035 millim. in 
diameter, and each shows a well defined nucleus and nucleolus, the latter being a mere 
speck. 
The larger cells occur sparingly ; they have a clear space round them, and are of 
moderate size, being about 0*019 millim. by 0*0093 millim. ; the nucleus generally 
measured 0*006 millim. in diameter, and the nucleolus 0*0017 millim. ; with these 
which were smooth and rounded or oval in outline, occurred others which were of 
irregular shape, with three processes ; these latter are rather smaller, measuring 
0*012 millim. by 0*008 millim., with a nucleus 0*003 millim. in diameter; some other 
cells which are still smaller, measuring 0*006 millim. by 0*007 millim., seem to form 
a transition to those of the smallest category mentioned above. 
Cerebellum. 
The cerebellum (fig. 1) has the usual structure of this lobe in Teleostei; here it is a 
tongue-shaped process directed forward, in which respect it differs from that of most 
Fishes, where as a rule it is turned backward, unless it is not sufficiently developed to 
MDOCCLXXXII. 
* Arch. f. Anatomie, 1835. 
6 D 
