352 WILLIAM NICOLL. 



burst open at the blunt pole aucl the larva is set free. This 

 is a small actively-moving Miracidium (Plate 21, fig. 6), not 

 differing much from the usual type. It measures "18 by "05 

 mm., and the body is differentiated into two distinct parts, a 

 head and a posterior part. The surface is completely covered 

 with long cilia. Near the centre of the head is situated a 

 large, dark, usually five-lobed pigment-spot (fig. 6 c.s.). 



I shall now proceed to define the genus of which this 

 species is to be regarded as the type. 



Genus Parorchis, mihi, 1907 (= Zeugorchis, mihi, 1906). 

 Body of moderate size and roughly oval outline, in the 

 contracted state differentiated into three regions, head, neck, 

 and hinder part, varying considerably in breadth. Anterior 

 part of ventral surface beset with strong spines and oral 

 sucker surrounded by an incomplete row of spines (or spines 

 entirely absent ?). Anterior part of body muscular, posterior 

 part more delicate. Suckers well developed ; ventral sucker 

 much larger than oral sucker. Intestine with short pre- 

 pharynx, powerful pharynx, oesophagus of considerable length 

 with irregularly sinuate walls, and diverticula which pass 

 round the outer side of the ventral sucker, then bend in 

 towards the middle of the body, and, after bending out 

 again, extend nearly to the hinder end ; usually somewhat 

 dilated at their termination. Excretory system consisting of 

 a small median, irregularly-shaped vesicle posteriorly, into 

 which open two median and two lateral excretory vessels ; 

 the latter are divided by septa into numerous lacuna?, and as 

 they pass forward branch into numerous smaller vessels. 

 Genital aperture median in front of ventral sucker. Cirrus- 

 pouch includes only the penis and the pars prostatica. Penis 

 beset with spines. Vesicula seminalis at some distance to 

 the rear, small, oval, extending a short way behind the 

 ventral sucker. Vagina well developed. Testes distinctly 

 lobed ; situated side by side, on approximately the same 

 level near the hinder end oi: the body. Ovary transversely 



believe, purely accidental. I liave not observed them in that situation 

 ar^ain. 



