18$ 



tliick walled cell, and it immediately Ijegius to increase in size 

 and assume a more I'ounded outline. The subsequent changes 

 lead up to the formation of what I regard as resting spores. The 

 yellowish-brown colouring matter which is at first diffused 

 throughout the body becomes concentrated in the nucleus, the 

 latter then assumes a brilliant i-ed colour : afterwards the nucleus 

 undergoes division, and either one or two orange-coloured spores 

 are formed, at the expense of the granular protoplasmic contents, 

 which gradually disappear as the spores increase in size. Unfor- 

 tunately I have not been able to ascertain what takes place after 

 the spores are fully formed, the specimens which I had under 

 observation having all remained in the same condition for tlie 

 last two months. The cell wall appears to resist the attacks of 

 the bacteria and infusoria, which exist in vast numbers in the 

 vessel containing them. 



This species made its appearance during the month of March 

 last in such vast nundjers as to render the water in Port Jackson 

 quite red, and for a period of six weeks the whole of the surface 

 water was more or less discoloured by the presence of this minute 

 organism. When viewed from a distance, the surface of the 

 water presented a variegated appearance, consisting of long 

 streaks and patches of glaucus-green, yellowish-brown, and blood- 

 red colour. The various streaks of red clianged about from time 

 to time owing no doubt to the direction of the wicid and tidal 

 currents. In nearly all the bays and small inlets the water on 

 the surface was quite thick with the organism, and if a bottle 

 full of water was taken up and allowed to stand for a few minutes, 

 there was a thick brown deposit formed at the bottom, consisting 

 of the bodies of the Glenodiniuni. 



Port Jackson, March, April, and May, 1891. 



Family Gymnodinida, Beryh. 



19. Gymnodi7dum spirale, Bergh, I.e., p. 1^23, pi. IG, f. 70-71. 



Kent, I.e. p. 858, Appendix. Biitschli, I.e. pi. 51, f. 5. (Plate 

 xxviii., fig. 8.) 

 During the months of April and May, this species was obtained 

 in abundance by dipping a tube into the water. To my mind it 

 appeared to be just as plentiful as the Glenodhmun, but owing 

 to its being transparent it did not perceptibly influence tlie colour 

 of the water. 



Hunter's Hill, Mossman's Bay, Woolloomooloo Bay, and Middle 

 Harbour. 



Class RHYNCHOFLAGELLATA, Lankester. 

 Family NocTiLUCiDiT;. 



20. Noctilnca viiliaris, Suriray ; Kent, I.e., p. ."597, pi. 1, f. 33-34. 

 It is with some hesitation that I venture to record this species. 



So far, I have not seen the flagellate form. The stationary form 



