40 



W. G. RIDEWOOD. 



extremity of the gastric diverticulum. It is divided by a median septum, wliicli is 

 readily recognisable between the pharynx and gastric caecum, and between the 

 intestine and the dorsal Ijody 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, l)ut not so far forward as 

 that shown in text-fig. 12, a lateral mesenteric fold is to l)e 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 liody at about 



CO. CO 



^3. 



--^nt. 4, 



Tbxt-Pigube 15. —Section of a jjolypide of Ccphalodiscus nigrescens taken transversely to the length of the body, and 

 passing through the basal end of the stolon. 



co.co. = coelomio contents, consisting of fine trabeculae and their nuclei, and entangled coelomic corpuscles ; 

 i. = intestine ; mu.7, mu.8 = muscle (see text) ; n.t.i = nerve tract ; s. = stomach ; rl, v2, v3 = blood-vessels 

 (see text). 



the level of the basal part of the backwardly directed stolon (text-fig. 15) shows 

 the trunk cavity occupied ])y 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. t. 4), partially divided into 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 



