Entozoa of IJritinh Murine Fishes. 1') 



culiclf of the hitter is often thrown into irrcgnlar wrinkles. 

 The constriction at the level of the testes, noted l)v Olsson, 

 is not of invariable occurrence, and the outline of preserved 

 (pressed) specimens is comparatively even. The colour 

 viewed by transmitted light is greenish yellow, darker 

 posteriorly from the i)rescnce of thr yolk-glands and golden 

 yellow centrally from the ova. 



The cntiilc is of no great thickness, devoid of spines, and 

 striated longitudinally and transversely. The suckers arc 

 fairly well developed : the oral sucker is subterminal and 

 globular, with a circular aperture ; its diameter is usually 

 about ,',, of the length of the body, but it is proportionately 

 larger in the younger examples than in the older, the 

 observed limits being -12 mm. in the smaller (TO mm.) 

 and -21) mm. in the largest (3-15 mm.). The ventral sucker 

 is more variable ; it is always elliptical in outline, vrith a 

 corresponding aperture, the long axis being transverse and 

 usually about half as long again as the diameter of the oral 

 sucker, i. e. I of the total body-length, but here again the 

 proportion decreases with increase in size. The measured 

 dimensions were •22-"42 mm. These figures agree very 

 closely with those of Odhner, viz. •12--25 mm. for the oral 

 and •25--44 mm. for the ventral sucker. Linton's American 

 specimens yield pretty much the same figures. 



Another feature to which some importance is attached is 

 the distance between the suckers (i. e. length of neck). My 

 observations coincide with those of Levinsen, viz. 1— [ of the 

 length of the body and ^ in young individuals. Odhner 

 also determines the limits at l,-^. 



The alimentary system conforms to the genus type, except 

 that a distinct piepharynx is present, first noted by Odhner. 

 It appears as a dilated tube about half as long as the pharynx 

 and considerably wider than the oesophagus. The pharynx 

 is almost globular, with a diameter of about -10 mm., but its 

 breadth usually exceeds its length slightly. The oesophagus 

 may be twice as long as the pharynx, but on contraction it 

 is bent in the form of an S, and appears short then. The 

 bending takes place either laterally or dorso-ventrally. 



The excretory vesicle is a long simple closed sac extending 

 as far forward as the level of the ovary, and opening pos- 

 teriorly by a tcrmiual pore. To it run down two narrow 

 convoluted tubules, one on cither side. 



The genital aperture lies almost midway between the 

 two suckers and also midway between the median line and 

 the extreme left edge of the body. It is thus to the left of 

 the asophagus and between the pharvnx and intestinal 



