200 NOTES ON THE FATOTA OF FALMOUTH. 



The occurrence of quantities of Noctiluca, together with a 

 fair number of Corycseus anglicus in the bay on the 3rd is inter- 

 esting. It seems to shew that this sudden rise in the surface 

 temperature of the inshore waters did not extend to any great 

 distance from the land, as the following observation wiU shew. 

 On the 14th, aided by a pleasant south-westerly wind, I sailed 

 into the bay and worked the tow-net at 11.30 a.m., just above the 

 bottom of the sea for fifteen minutes in 25 fathoms of water. The 

 temperatures recorded were as follows : — surface, 60°F. ; bottom, 

 25 fms., Se-e^'F. ; surface temperature of sea in the harbour, at 2 

 p.m., on my return, 65°!P. 



On examining this gathering I found it teeming with Noc- 

 tiluca. I was always hitherto under the impression that tliis 

 Infusorian was purely a pelagic form ; but this result seems to 

 indicate that the species does descend into the cooler layers of the 

 sea at will. I have looked in vain in various works devoted to 

 the description of these lowly forms, but have failed to find any 

 notice of this singular habit ; all writers simply stating that it is 

 pelagic. I may mention that no special precautions were taken to 

 exclude the inclusion of other forms during the passage of the 

 net to and from the surface. Fortunately, I brought back with 

 me a jar filled with sea- water taken from the surface of the sea 

 where this gathering was made, and no Noctiluca could be found 

 therein. The two next days were calm, so I could not sail into 

 the bay. At 1.15 p.m I made a short tow-net gathering in the 

 harbour during high- water, but not a single specimen of Noctiluca 

 could be found. It was not till the 1 8th that specimens of this 

 Infusorian occurred in the harbour, and from that date till the 

 end of the month they formed a constant feature in the tow-net. 



In the same gathering quite a number of Ceratium tripos, 

 C. macroceros, and C. fuscus were also detected. I have only on 

 one previous occasion detected specimens of this last named 

 speciesin my tow-net, that occasion being duringthe springof 1893. 

 On the 23rd of March of that year the tow-net was worked in the 

 harbour after prolonged easterly winds, and two or three speci- 

 mens of Ceratium fuscus were observed in that gathering. In my 

 notes on the Fauna of Falmouth for that year'*^ I recorded the 

 presence of this rare species of Infusorian. 



