102 CEYLON PEARL OYSTER REPORT. 



Schistorchis carneus, n. sp. Plates I. and II., figs. 9 to 12. 



Specific diagnosis. Blood red tinted during lifetime, about 1 millims. to 15 millims. 

 long, and about 4 millims. to 6 millims broad. Diameter of the oral sucker about 

 2 millims. to 2 5 millims., of the ventral sucker about 0"8 millim. to l'O millim. The 

 oral sucker, in all the specimens examined, somewhat retracted, not reaching the outer 

 surface of the body. Distance between the two suckers at the most - 9 millim. 



Pharynx much broader than long, 0'8 millim. by 0'3 millim. in the largest specimen, 

 0"(3 millim. by 0"3 millim. in a smaller one. The intestinal coeca run in the beginning 

 transversely outwards, then, after turning in almost a right angle, slightly convergent 

 to the posterior end of the body. In several specimens they are filled with a dark 

 matter. The paired branches of the excretory vesicle cross the transversely running 

 beginnings of the intestinal coeca, and finish at the level of the greatest diameter 

 of the oral sucker. 



Diameter of the single testes reach 0"G millim. to 1*0 millim. in the largest 

 specimen. Cirrus-pouch with a large vesicula seminalis, which lies in the median 

 line just behind the ventral sucker and opens in the pars-prostatica, turning round 

 the left side of the sucker. Ovary near the median line, just behind the cirrus-pouch, 

 and of about the same size as the single testes. Receptaculum seminis behind the 

 ovary or at the left of it. Both ovary and receptaculum seminis in the triangle 

 between the paired branches of the excretory vesicle, which unite just behind them. 

 Vitellarium beginning at the level of the ovarium or of the vesicula seminis. 



From the stomach of Tetrodon stellatus, Gunther ; from South Modragam Paar, 

 Ceylon Pearl Banks. Eleven specimens. 



General Remarks on Distomids with Numerous Testes. 



Already several genera of Distomids with an increased number of testes are known. 

 With some of these, Syncoelium, Lss., Otiotrema, Setti, Hapalotrema, Lss., this new 

 genus has no affinity at all. Also with the above-named Gorgodera, Lss., it has no 

 close resemblance beyond the number and arrangement of the testes. However, the 

 resemblance is far greater with the genus Pleorchis, Raill., the anatomy of which, 

 it is true, is but little known as yet ; but the general arrangement of the genital 

 organs is the same in Pleorchis as in Sinistorchis. The two species of Pleorchis 

 also being intestinal parasites of marine fishes, it seems quite possible that the new 

 genus is allied to Pleorchis, which differs, however, from it in several important 

 points, justifying the creation of a new genus for the Ceylonese species described 

 above. For Pleorchis is provided with spines in the cuticula, with a greater number 

 of testes (24 to 30), with a long pra^pharynx, and with anterior branches of the 

 intestinal coeca, similar to, though smaller than, the anterior branches of the H-shaped 

 intestine of Accaccelinm. 



Referring to the species of Pleorchis, I must justify the mention of two species, 



