100 CEYLON PEARL OYSTER REPORT. 



the stomach, most to one or other side, a few above the roof of this organ. One 

 individual was found beneath the mouth in the substance of the labial palps. 



Out of a further lot of 1G dissected on 7th November, 1902, and coming from 

 North-east Cheval Paar, 5 contained this species of Nematode. As many as 5 of 

 these worms were found in one individual ; 3 were within the gonad, a fourth was 

 contained in a large cyst in the palpar region of the mantle close to the pallial line. 



In a second pearl oyster, 2 Nematodes were found in the gonad. A third and 

 fourth each had one encysted in the same region, while in a fifth the Nematode cyst 

 was in the mantle. 



On 14th November, 1902, 4.. pearl oysters from South-west Cheval yielded but 3 

 individuals harbouring this parasite, found in each case in the gonad. In another 

 lot, one individual had one of these Ascarids in a cyst in the antero- ventral region 

 of the mantle. 



On 5th November, none were found in 30 oysters from South-east Cheval, and on 

 Gth November, none in 1 5 oysters from the same. 



On 11th November, two out of 20 dissected oysters from North-west Cheval yielded 

 each 1 Nematode from the gonad. 



On 12 November, 20 oysters from West Cheval gave but one, which contained this 

 parasite. It was encysted within the wall of the stomach. 



On 15th and lGth November, none were found in Gl pearl oysters from South- 

 east Cheval. 



On the 18th and 20th November, none were yielded by the dissection of 55 

 individuals from the Dutch Modragam and Muttuvaratu Paars. 



On 3rd and 4th February, 1903, 5 individuals out of 83 dissected oysters from 

 South-east Cheval showed 1 Nematode each in the gonad. 



On 8th and 13th February, 1903, 3 oysters only were infected out of a lot of 120 

 dissected from North-east Cheval, in each case the cyst was within the gonad. 



Of 15 oysters dissected on 11th February, 1903, from Periya Paar Kerrai, 1 only 

 yielded an Ascarid, found in the usual position. 



On 12th February, 1903, 32 oysters from the North Cheval contained no trace 

 of this worm. 



Of a total of 534 pearl oysters dissected specially in search for Nematodes, 30 

 individuals yielded specimens of this species. 



The cysts were usually of distinct pyriform outline, flattened laterally. Occasion- 

 ally the form was irregular. 



Cheiracanthus vmcinatus, Molin. Plate III., figs. 41, 44, 45, 4G, 47, and 48. 

 Echinocephalus uncinatus, Molin, ' Denk. Ak. Wien,' XIX., 1861, 2nd Abth., p. 311. 



Tbia Nematode was also in a larval state. The specimens averaged 12 8 millims. 

 in length and 0'43 millim. in breadth, The cuticle is swollen. On the thickened 



