40 W. G. RIDEWOOD. 
extremity of the gastric diverticulum. It is divided by a median septum, which is 
readily recognisable between the pharynx and gastric caecum, and between the 
intestine and the dorsal body wall, but not between the gastric caecum and the 
intestine, these being found to be invariably in close contact. In sections taken 
farther forward than that represented in text-fig. 13, but not so far forward as 
that shown in text-fig. 12, a lateral mesenteric fold is to be seen extending outward 
to the gonad duct from the median septum that extends from the dorsal wall of 
the pharynx to the intestine. 
A section taken transversely through the hinder part of the body at about 
Text-Ficure 15,—Section of a polypide of Cephalodiscus nigrescens taken transversely to the length of the body, and 
passing through the basal end of the stolon. 
co.co. = coelomic contents, consisting of fine trabeculae and their nuclei, and entangled coelomic corpuscles ; 
2. = Intestine ; mu.7, mu.8 = muscle (see text); .f.4 = nerve tract; s.=stomach; v1, v2, v8 = blood-vessels 
(see text). 
the level of the basal part of the backwardly directed stolon (text-fig. 15) shows 
the trunk cavity occupied by the flattened stomach and intestine. The stolon 
itself is nearly circular in section, and its ventral epithelium is composed of 
smaller and less deeply pigmented cells than the dorsal and lateral parts. A 
nerve tract (n. ¢. 4), partially divided imto three, is seen adjacent to the small 
epithelium cells of the ventral surface. The coelomic cavity of the stolon is largely 
obliterated by a mass of compacted trabeculae and their nuclei, with entangled 
