NARRATIVE. 81 



Crustacea and much Trichodesmium erythrceum. Twenty-four species of < lopepoda 

 have already been identified by Mr. Andrew Scott from this hauL 



The deep Tow-net brought up Sagitta, a violet Appendicularian, filamentous Algse 

 forming balls, a large new Ostracod, and 15 species of Copepoda including Clauso- 

 calanus furcatus and Ectinosoma atlanticum. 



In the evening, at 9 P.M., the sea was dotted with bright phosphorescent lights of 

 considerable size singly placed at some distance apart. These for over an hour 

 continued to glow with a pulsating appearance in harmony all shining brightly at 

 the same moment, and then all flickering out together, to re-appear simultaneously a 

 few seconds later. We went out at once with a net and obtained a sample of the 

 plankton, but could not be sure that we had caught any of the pulsating forms. The 

 gathering contained Sagitta (very many), Appendictdaria, Copepoda half-a-dozen 

 common species and Sapphirkina sinuicauda, Pontella fera, Calocalaniis pavo and 

 some smaller forms, along with half a-dozen one-inch-long Heteronereids of a reddish- 

 brown colour. We suspected the light to be due to the last-named, and if that is so, 

 possibly the periodicity was a result of the epitocous condition and was accompanied 

 by a simultaneous discharge of genital products. 



On March 14th, at 7 AM., at the southern end of Pamban Pass, the sea-temperature 

 was 82 0, 5 F. (5 degrees higher than it was at the same spot on February 5th) ami 

 the specific gravity was 1"022. At 6 p.m. in Palk Bay, the sea-temperature was 

 again 82'5 F. (4^- degrees higher than on February 6th) and the specific gravity 

 was 1 '02 1. We anchored for a couple of hours one mile off the village of Rameswaram 

 and lauded in the boat, examining the beach, the coral shoals on the way in, and the 

 raised coral platform along the shore alluded to by Thurston ('Notes on the Pearl 

 and Chank Fisheries, &c.,' Madras Museum, 1890). 



Two long hauls of the large shrimp-trawl were now taken in Palk Bay on the way 

 across to Jaffna. The first was over the same region trawled on February 6th 

 (Station XVIII.), but at right angles to our former course (see fig. 22). Starting due 

 east of Rameswaram, about 4|- miles off shore at a depth of 5 fathoms, we towed for 

 about 10 miles to the north-east, towards the island of Catchetivo, the water deepening 

 gradually to 7 fathoms. The bottom was soft grey-blue mud, containing small 

 concretionary nodules and many casts of the interior of Gastropod shells. The 

 animals obtained were mostly the same fish and invertebrates as on February 6th, a 

 few small Crabs, Molluscs and Echinids ; also a species of Arcania with large lateral 

 projections of a deep violet colour on the carapace. Several pearl ovsters were 

 obtained in this haul, and a sea-snake. 



The second haul was taken to the south-east of Catchetivo Island, in a depth of 

 7 fathoms. The trawl was worked rather more rapidly with the result that it did 

 not hug the bottom so closely, and brought up no mud and very few invertebrates, 

 but a large haul of small Scopelid fishes which filled half-a-dozen ship's buckets and 

 numbered over 2500 specimens. They apparently belonged to only 3 or 4 species 



M 



