NOTES ON THE FAUNA OF FALMOUTH. 199 



The presence of an unknown species of Oscillatoria in vary- 

 ing quantities in tlie tow-net from tlie 25th of May to the 10th 

 of September, when my observations for a time were discontinued, 

 is of interest. This alga was most obundant in the sea during 

 August. Copepods were very scarce during the whole of this 

 month. 



On the 13th three beautiful Bipennaria formed the most 

 important forms in the tow-net. 



Noctiluca reappeared in the bay on the 23rd, and with them 

 one metazoea stage of Porcellana longicornis was noticed. Another 

 specimen of the same crustacean was secured on the 28th. 



On the 30th I made two surface gatherings in the bay. The 

 tow-net was kept out on both occasions for 1 5 minutes, and the 

 localities where these gatherings were taken were separated by a 

 space of at least two miles. In the first collection a few Noctiluca 

 and Ceratium tripos were seen with other forms, but in the second 

 haul they were wanting. This fact clearly shews that one must 

 not conclude that the absence of any given form from the tow-net 

 signifies that it is not to be found in the neighbourhood, but only 

 that it is not present in that portion of the sea where the tow-net 

 was worked at the time named. The surface temperature of the 

 sea was identical in both places, being 55"6°r. 



The decrease of the two diatoms Ehizosonelia, and Chsetoceros 

 during this month is noteworthy ; Ceratium tripos appearing in 

 their stead. 



July. It was not till the 6th of the month that summer really 

 began. During the following nine weeks we enjoyed warm 

 weather and almost continuous sunshine. Unfortunately the 

 prevailing winds were from the north, and as a natural conse- 

 quence the pelagic fauna was wanting in oceanic forms. 



The rapid rise in the surface temperature of the sea during 

 the early part of this month is interesting. On the 1st the 

 temperature was SS^F., on the 3rd 55-9T. ; 4th, at 4 p.m., high 

 water, 62-3° F. ; 5th, 58-6°F. ; 6th, 60°F. ; 9th, 61° F.; 

 16th, 63''F. ; 17th, 65-3°F. There was a slight faU in the sur- 

 face temperature on and after the 19th to 62"F., and on the 23rd, 

 a stiU further reduction to 6r3°F. ; rising again to 62°F. on the 

 last day of the month. 



