932 
MR. A. SANDERS ON THE ANATOMY OF THE 
Cerebral Lobes . 
These lobes resemble in structure the corresponding parts in M. cephalus. Each 
lobe is partially divided into two by a transverse horizontal depression, which separates 
a rounded dorsal knob from the ventral portion. The olfactory peduncle is attached 
to a minute oval eminence situated at the inferior edge of the anterior part of the 
ventral lobe. Externally there is a single layer of epithelial cells, each sending a long 
process into the substance of the lobe perpendicular to the surface; within this there 
is a layer of small cells, sharply defined at parts from the central portions of the lobe. 
These cells are packed close together with a comparatively small quantity of neuroglia 
between them; many of them measure from 0’006 millim. to 0'0083 millim. in diameter; 
others are more oval in shape ; the majority show a nucleus and a nucleolus; in some 
places they are separated from the central portion by a layer of fine transversely directed 
fibrillse. This layer is shown in my paper on the brain of Teleostei. * * * § 
FritschI is of opinion that these cells belong to the connective tissue elements, 
and compares them to the lay er of granular neuroglia which bounds the grey matter of 
the cerebrum externally in Mammalia; but to me they seem to present the characteristics 
of nerve cells, although this is a point which is often difficult to determine; in 
M. cephalus they certainly do not join the processes from the epithelial cells, which 
they ought to do if they were connective tissue elements. If they are nerve cells 
the layer of neuroglia referred to by Fkitsch is not present in the brain of Teleostei, 
although a corresponding one is found in the brain of the Elasmobranchii. 
The central portion of these lobes (br.br.) is occupied principally by neuroglia of a 
granular appearance in which are dispersed at intervals cells of a larger size than 
those of the outer layer. They measure generally about 0'016 millim. by 0*012 millim., 
with a nucleus 0*008 millim. by 0*006 millim. ; they mostly have a smooth outline with 
about three processes. A few were occasionally met with which possessed an irregular 
outline with five or six processes. Bound each cell there was ordinarily to be seen a 
clear space; concerning the nature of this space anatomists are by no means clear; 
BollJ considers that it is an artificial production ; Obersteiner§ mentioned several 
reasons in favour of the view that it is natural; Henle|| and Eorel1[ are entirely of this 
opinion ; for myself I am undecided at present. In the Mormyridce these spaces cer¬ 
tainly do not present so natural an appearance as they had in M. cephalus. Perhaps 
sections of frozen brain tissue might decide the point, though this is by no means 
* Log. tit., Plate 63, fig. 17. 
| Untersucbungen ii. den feineren Ban des Fischgehirns. Page 48. 
1 Die Histiologie n. Histiogenese d. Nervosen central organe. Archiy f. Psychiatrie, Bd. iv. 
§ Beit. z. Kentniss yom feineren Ban der Kleinhirn. Sitzb. d. Matli-Nat. Classe d. k. Akad. der 
Wissenscbaft, Wien. Bd. lx. 
|| Nervenlelire. 
TJntersncli, ii. d. Hanberegion, &c. Arcbiv. f. Psychiatrie, Bd. vii., 1877, p. 449, 
