TREMATOPE PARASITES. 99 



Stephanochasmus ceylonicus, n. sp. Plate I., figs. 4 to 6. 



From the subcutaneous tissue of Narcine timlei, HENLE, taken off Dutch Bay, 

 Ceylon. Several specimens. 



Of this species only the encysted larval form was found, but there can be no doubt 

 that the species is a new one, although closely allied to Stephanochasmus pristis 

 (DESLONGCH.). 



The specimens are about 2'0 millims. to 2 '6 millims. in length, and 0'25 millim. 

 broad. Margins of oral sucker projecting laterally over the thinner neck. Diameter 

 of oral sucker 0*18 millim. to 0'2 millim., of ventral sucker 0'18 millim. Distance 

 between the two suckers 0'6 millim. Length of prsepharynx 0'4 millim. Pharynx 

 0*126 millim. in length, and 0'056 millim. broad. Round the mouth a double wreath 

 of 36 large spines, which is not interrupted ventrally, as it is in Stephanochasmus 

 cesticillus (MoLiisr). The larger spines of the first row are 0*059 millim. and the 

 somewhat smaller spines of the second row are 0'056 millim. in length. The small 

 spines of the general body surface are best developed close behind the oral sucker, 

 and become gradually smaller posteriorly, though more numerous. Behind the 

 level of the ventral sucker the skin acquires the finely spinous structure described 

 by Looss for HcBmatoloechus asper, Lss., and the posterior half of the body is smooth. 

 Of the genital organs only the two testes, situated near the posterior end, are visible. 

 The excretory vesicle is Y-shaped, with a short but ample median trunk, and two 

 long branches reaching almost to the oral sucker. 



The worms were encysted in round cysts, with a diameter of the outer wall of 

 about 0'5 millim. to 0'8 millim., and of the inner wall of about 0'36 millim. to 

 0*47 millim. According to Mr. JAMES HORNELL, who collected the worms and has 

 made drawings from the living objects, the fluid filling the space in the cyst around 

 the larva was granular. In an uninjured cyst which I examined this fluid seemed 

 quite clear. 



SUB-FAMILY : ACANTHOCOLPINvE, nov. 



Provisional diagnosis. Distomids with a very elongate and but slightly muscular 

 body, whose cross- section is round or oval. Ventral sucker near the anterior end 

 of the body. Oral sucker terminal or subterminal, but always cup-shaped, never 

 funnel-shaped, followed mostly by a very distinct tubular praepharynx. Pharynx 

 well developed, oesophagus short, intestinal cceca long, reaching almost to the 

 posterior end of the body. 



The two testes situated in the posterior part of the body, one behind the other, 

 their axial diameter longer, more or less, than their transverse diameters. Cirrus- 

 pouch long and slender, cirrus with spines. Ovary in front of the testes, median or 

 sub-median. Vitellarium formed by numerous little follicles, situated on the sides 

 of the body and behind the testes (in Stephanochasmus and Acanthocolpus) or only 



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