THE PAEASITES OF THE PEARL OYSTEE. 95 



li is probable tliat this species is protogynous, for while the testes are .-is yet 

 empty, the ovary is densely packed with granular tissue. In the present resting 

 condition the former organs appear as two paired ovoid sacs, clear, and with no 

 distinguishable contents. They lie immediately posterior to the ventral sucker. 

 Behind the left testis lies the globular ovary, opaque with the mass of its crowded 

 granular contents. 



The copulatory organs lie near the anterior end of the body. They open side by 

 side just behind the oesophageal dilatation. The penis-sheath (p.sh.) has a nearly 

 median position; the vagina lies a little to the left. The former is cylindrical, 

 showing the rudiment of a seminal vesicle (s.v.). The vagina is slightly curved and 

 appears to have glandular walls. The uterus (ut.) is barely distinguishable in pressure 

 preparations as a long, transparent coiled tube running from the base of the vagina 

 backwards to connect with the ovary. Vasa deferentia are not to be made out. 



In many respects this larval form conforms to the characters of Looss' suit-family 

 Philophthalminje.* It is a larval form, so that the difference in size is immaterial. 

 More important is the fact that the testes in the new species are, roughly speaking, 

 on a level, not one behind the other, and that they are before, and not behind the 

 ovary, as they are in the Philophthalminse. The members of this family live, according 

 to Looss, " An geschiitzten Stellen der Korperoberflache bei Vogeln." 



Until we have succeeded in tracing the life-history of this form, it would be unwise 

 to dogmatize as to its systematic position. We have, however, little doubt that it is 

 a new genus ; and we have named it after Musali, the district of which the pearl 

 fishery coast is part. The Adigar of Musali is the native official responsible for all 

 details when a fishery camp is being organized. The present holder of the office, 

 Mr. V. Vraspillai, typifies everything that is best in the headman system in vogue 

 in ( !eylon. 



3. Aspidogaster margaritiferae, n. sp. Plate IV., figs. GO, 61, G2, 66, 68, 69. 



Length in immature specimens G millims., colour brown ochre dorsally, but the foot 

 has a beautiful rose-red hue. Four rows of alveoli or suckers.on the foot arranged 

 alternately ; the number of alveoli is not precisely known, it probably increases with 

 age, but there are something like 20 in the outer rows and 18 in the two median 

 rows. A number of " tube-feet" project from the area between the outer rows and 

 the middle rows and between the two central rows. There are none on the outer side 

 of the outer rows. 



Habitat. Pericardial cavity of Margaritifera vulgaris, Schum. Taken at the 

 < iheval Paar, Cevlon. 



Three specimens of this Trematode, closely related to Aspidogaster conchicola, were 

 found within the pericardial chambers of pearl oysters from the south and south-east 



* ' Zool. Jahrb. Syst.,' XII., 1899, p. 586. 



