Two New Trematodes of the Family Gyrodactylida?. 7 



at some distance from the front end of the body and leads into a 

 rather spacious mouth cavity into which the pharynx protrudes, 

 and which consists of two portions, a short tubular portion 

 continued inwards from the mouth and lined by a cuticle similar 

 to that of the body surface and a posterior expanded portion lined 

 by a very thin structureless membrane. The mouth cavity 

 extends further backwards on the ventral side of the pharynx 

 than on the dorsal. As above mentioned the mouth is provided. 

 with a sphincter and in life is seen to close and open rapidly. 

 The pharynx is an ellipsoidal muscular organ with a thick wall and 

 a narrow lumen lined by a réfringent structureless membrane of 

 some thickness, and triradiate in cross section. There are on the 

 front margin of the pharynx six papilla?, on which the pharyngeal 

 glands open. These are large cells occupying the interspaces of 

 the muscular libres of the pharyngeal wall, with coarsely granular 

 contents, which stain deeply with haematoxylin, floating in a 

 hyaline medium; the nuclei are vesicular and usually contain a 

 conspicuous chromatin mass. The musculature of the pharynx is 

 very well developed and consists almostly entirely of radial fibres. 

 The circular fibres appear to be very weakly developed im- 

 mediately inside the outer limiting membrane of the pharynx as 

 well as around the anterior part of the lumen. Fine isolated 

 meridional fibres are also present here and there. In sagittal 

 sections of the worm the ventral wall of the pharynx is much 

 thicker than the dorsal. The interspaces left by the tissues above 

 mentioned are filled by very delicate reticulated connective tissue. 

 The pharynx is followed by a very short œsophagus lined by 

 an epithelium exactly similar to that of the intestine; into it open 

 the unicellular salivary glands, which are situated in two groups, 

 one on either side of the body about midway between the dorsal 

 and ventral sides and dorsally to the outer pair of cephalic glands 

 mentioned before. The cells are large and contain a coarsely 

 granular substance staining well with haematexylin but not with 

 orange and therefore conspicuously different from the cephalic 

 glands in sections; the nuclei are vesicular and mostly contain a 

 chromatin mass. The ducts are comparatively long but distinctly 



