410 THOS. H. MONTGOMERY jr., 
apparently do not form a ring commissure above the intestine nor in 
the eye sheath. No chromophobic cells lie above the ventral com- 
missure, which is composed of fibres exclusively, and few or no 
chromophilic nerve cells. Hence there is no supra-oesophageal ganglion 
present, i. e. no brain in the strict morphological sense, the cephalic 
ganglion being altogether infra-oesophageal. This cephalic ganglion is 
therefore of a very simple type. 
In a male individual which was carefully examined the cephalic 
ganglion (Fig. 3, Pl. 37) showed essentially the same structure as in 
the female, though there were a few differences as follows: the ganglion 
is dorso-ventrally thicker than the nerve cord; each cephalic nerve 
(Ceph. N) subdivides at its anterior end into three branches the most 
posterior of which is the smallest; and each cephalic nerve gives off 
three ventral nerves (N.2) to the hypodermis. 
The elements of the cephalic ganglion are the same as those in 
the nerve cord, chromophilic nerve cells and their fibres, and chromo- 
phobic cells and their fibres. Apparently these cells have the same 
form and structure as those of the cord. A count of the number of 
the giant chromophobic cells in the ganglion of a female showed: 
14—16 on the left, 7—11 in the median line, and 7—13 on the right, 
a total of from 28 to 40 in all; these giant cells showed an irregular 
distribution. 
C. The Cloacal Ganglion of the Female. 
The cloacal ganglion is the enlarged posterior end of the ventral 
nerve cord, and is placed in the mid-ventral line just anterior to the 
point of bifurcation of the lateral tail lobes (Cl.G Fig. 72, PI. 41). 
It is connected ventrally (Fig. 36, Pl. 39) by the here broadened 
neural lamella with the hypodermis (Hyp) of the body wall, and 
dorsally it is in direct contact with the epithelium of the cloaca 
(Cl. Hpi). It may be said to commence anteriorly where it first comes 
into contact with the cloacal wall, and has a length of about 120 w. 
At its middle point it is ovoid on cross section, widest dorsally, and 
here bulges upward the wall of the cloaca (Fig. 72, Pl. 41); at its 
posterior termination it is narrowly compressed laterally. It is thus 
fitted into the angle made by the junction of the lateral tail lobes. 
From it arise nerves, the anterior cloacal nerves, which 
course forwards in the wall of the cloaca; and the posterior 
cloacal nerves, which course backwards (caudad) within the wall 
of the cloacal lining of the lateral tail lobes. 
