24 Art. 4. — S. Goto and H. Kikuchi : 



body, being about 2.5/*, and almost liomogeneous in appearance. 

 The dermal glands are present at both ends of the body but less 

 well developed than in Dactylogyrus. The cephalic (/lands of either 

 side open by three groups of ducts on the top of the tentacle-like 

 processes already mentioned, two for the inner and one for the 

 outer (fig. 11). The cells are situated 'in two groups on either side 

 of the body, an anterior group of fairly numerous cells directly 

 on the outer side of the mouth cavity and a posterior group of 

 fewer cells on the outer side of the. posterior half of the pharynx 

 or further backwards. The ducts of the posterior group are 

 naturally longer and the outer tentacle-like proeess receives ducts 

 from both groups. Besides secreting mucus these gland cells give 

 rise to small rod-like bodies with well defined outlines (rhabdites). 

 Similar bodies have been observed by Maclaren in Diplectanum 

 and by Wacke in Temnocephala. The secretion of the cephalic 

 glands stains well with eosin or borax carmin but not with 

 h Hematoxylin. The cells of the anterior group may be as large as 

 10// by 19//, those of the posterior group 24-29/* by 17//. The 

 caudal glands are situated in the caudal portion posterior to the 

 intestinal cœca; the cells are pyriform and provided with efferent 

 ducts which unite into a large duct on either side of the body and 

 open on the caudal disk, nearer to the ventral side close to the 

 hooks. The cytoplasm of these cells are either deeply or faintly 

 stained according to the stages of their secretory activity; the 

 nuclei are vesicular and contain a chromatin mass; the size of 

 the cells may be 19// by 12//. 



The transversely oval caudal disk measures 0.12 mm. by 

 0.01) mm. and bears near its centre two pairs of hooks, whose 

 apices are directed one pair ventrally the other dorsally, although 

 their positions can be altered in various ways by the action of the 

 muscles attached to them (fig. 12). They are nearly alike in 

 form, but the dorsal pair appear to be always slightly larger than 

 the other and to be situated on the outer side. Each hook is 

 flattened and consists of an asymmetrically V-shaped body with 

 longitudinal surface striations and a sharp bent claw projecting 

 from the apev of the V like the beak of a falcon and provided with 



