28 CEYLON PEARL OYSTER REPORT. 



Holothuria atra, Ophiocnemis marmorata ; 



Phyllodocc foliosopapillata n. sp. (Horxell), Lepidonotus trissochcetus, L. carinu- 

 lalus, Panthalis mdanonotus (in sandy gelatinous tubes) ; 



"Suran," Avicula sp. ; 



Asymmetron (lletcropleuron) cingalense (12 specimens). 



Of the numerous small pearl oysters in this haul rather more than half (on the 

 average 11 to 9) were dead, many of them entangled with " Suran." 



Several hauls of the tow-net were made during the day (February 4), and amongst 

 the most abundant organisms noticed were : - 



Diatoms (vast quantities), Ceratium, Peridinium, and spherical gelatinous Alga?. 



Mitraria, Nauplei, and other larvae ; 



Copepods (29 species), Oiihona similis, Calanus minor, Pseudodiaptomus aurivillit, 

 Pontellopsis strenua and P. perspicax, Calanopia elliptica, Labidocera acuta, Tortanus 

 forcipatus, Centropagcs sp. (new to science) ; 



Sal pa democratica-mucronata. 



The blue Copepods and Salpa were mainly in the later more westerly hauls 

 (18 miles from shore), and the Diatoms and Alga? in the earlier hauls on the Cheval 

 paars. A gathering taken during "the night gave some large Sagitta, a few small 

 Medusa?, some Amphipods and Nebalia. 



Having now made a preliminary examination of the pearl-hank regions in the Gulf 

 of Manaar and obtained some samples, I decided to visit various other localities round 

 the island to which attention has been directed either by the literature of the 

 subject or by information obtained since landing in Ceylon. We therefore made 

 our way next through the Pamban Pass, between Rameswaram Island and the 

 mainland of India, into Palk Bay, which lies north of Adam's Bridge (see map of 

 route, p. 19). 



On February 5th, while lying at the southern end of the passage, waiting for the 

 pilot, the sea-temperature at 10.30 a.m. was 77 "5 F.. and the specific gravity was 

 T0205. A tow-net gathering taken here contained a new species of Centropages, 

 with a remarkable dorsal spine, and a new species of Labidocera. 



On February 6th, at the north end of the pass, opposite the village of Pamban, at 

 7 a.m., the sea-temperature was 76 F. and the specific gravity only 1 "0 1 'J ; at 7 p.m. 

 in the middle of Palk Bay the sea-temperature was 78 F. and the specific gravity 

 I '021. This day was spent trawling and dredging in Palk Bay, a wide shallow area 

 lying between Adam's Bridge and the northern end of Ceylon, and partly enclosed by 

 the chain of islands extending southwards from Jaffna, with, for the most part, a 

 muddy bottom at a depth of from 6 to 8 fathoms. Parts of it near the islands are much- 

 blocked, as we found later, by luxuriant coral growths, but the centre presents a large 

 open expanse with a uniform soft bottom suitable for trawling. Pearl oysters are said 

 to bs found in a few feet of water in some places round the shore, but there are no 

 fisheries, and our object here was not to look for "paars" but i'or fish, as I had under- 



