THE PARASITES OE THE PEARL OYSTER. !)3 



Both of the copulatory organs are present and well developed. They open side 

 by side to the immediate right of the ventral sucker at about the level of its 

 centre. That of the male consists of a great cylindrical penis-sheath (p.sh.) lying, 

 in great part, posterior to the ventral sucker. It contains a well-defined seminal 

 vesicle (s.v.) at the posterior end together with the rudiments of the penis itself. 

 The distal portion of the sheath is somewhat narrowed to form a distinct neck. 



The female organ, the vagina, lies to the right, alongside and parallel with the 

 penis-sheath. The walls are thrown into a number of circular folds or pleats wide 

 grooves, concave in section, alternating with sharp-angled encompassing projecting 

 folds that give it much the appearance of a broadly spindle-shaped Chinese lantern, 

 No trace of uterus can be made out. 



The encysted cercarise of this Trematode resemble those figured and described by 

 Jameson in some features, but differ from them in other particulars, which indeed 

 exclude it from the sub-family Brachycoelinaj to which Leucithodendrium belongs, 

 e.g., the two branches of the alimentary canal extend far beyond the ventral sucker, 

 and indeed reach almost to the binder end of the body. 



It is difficult to establish a nsw genus upon a form which is not yet adult, but 

 after going through the twelve sub-families into which Looss* has split up the 

 Distomidae we cannot bring our specimens into line with any of them. Some of their 

 characters appear in one sub-family and some in another, but the totality of 

 characters does not appear in any one of them. Owing to the immaturity, several of the 

 chief features of the adult anatomy, such as the disposition of the uterus, could not 

 be made out. 



The increasing difficulty of coining names hitherto unoccupied has induced us to 

 fall back on Tamil, and we suggest the name Muttv.a (Muttu means a pearl) for the 

 genus. This will recall the particular paar (Muttuvaratu) where it occurs in the 

 greatest abundance. 



5. Kusalia herdmani, n. gen. and n. sp. Plate III., fig. 51, and Plate IV., 

 figs. 58, 59, and 65. 



Skin smooth, without denticles. Pharynx rather smaller than oral sucker. Ventral 

 sucker very large and protrusible ; its diameter, as compared with that of the oral, is 

 as 7 : 3. (Esophagus very short, a median backward pouch projects between the 

 origin of the two limbs of the alimentary canal. The latter are long and reach back 

 to the end of the body. The reproductive openings lie between the ventral sucker 

 and the oral, but nearer the latter. The testes lie behind the ventral sucker and are 

 inclined at an angle one to another, the ovary lies behind them. Excretory bladder 

 small and triangular. 



Habitat : The larval encysted stage is found in Margaritifera vulgaris, Schum., 

 encapsuled in the muscles, the mantle, and the foot. 



* 'Zool, Jahrb. Syst.,' XII., 1899, p. 522, 



