NOTES ON THE FAUNA OF FALMOUTH. 265 



June. The weather during this month contined exceptionally 

 fine and warm. The following variations in the suface temper- 

 ature of the sea were observed during this period : — 1st, 60*'F.; 

 5th, 60°3 F.; 8th, 61 °6 F.; 10th, 62''F. From this date till the 

 end of the month the surface temperature of the sea remained 

 very uniform, varying from 60'^9 F. on the l7th to 62°F. on the 

 30th. 



The prevailing northerly winds were again observed to have 

 an appreciable effect on the floating fauna both in the bay and 

 harbour. 



During the first few days of this month, Phialidium 

 temporarium (Browne) were very abundant in the harbour ; and 

 by the 11th not one specimen could be captured either by the 

 tow-net or by means of dipping from my boat. The next day in 

 a gathering made in the bay no medusoe were observed. Sagitta 

 bipunctata, Corycceus anglicus, and Dias longiremus, were 

 found to be fairly numerous. Not more than two or three 

 specimens of Centropages typicus were observed. 



During the past four years I have secured in my tow-net 

 during this season of the year a very interesting Ectoparastic 

 Isopod attached usually to the back of Oalanus finmarchieus, 

 Clausia elongata, and Temora longicornis. The animal is figured 

 and described by the Rev. Thomas E. E. Stebbing'"* as 

 Microniscus calani, Sars., and on comparing my specimens with 

 the brief description given in that gentleman's book they seem 

 identical. Owing to the extreme minuteness of these animals, the 

 largest hardly measuring 2 m.m. in length, they are exceedingly 

 difficult to detect, so it is quite possible that I have on several 

 occasions failed to identify them when they were present in my 

 tow-net gatherings. 



It seems that Microniscus is able to detach and refix itself 

 to any passing copepod ; for on one occasion a single specimen 

 of Calanus finmarchieus was isolated in a watch glass with an 

 individual on its back. With a needle I transfixed the copepod 

 and with another removed the parasite without apparent damage, 

 I then introduced a specimen of Clausia elongata, and in an 

 instant the Microniscus fixed itself to the back of the new host. 

 This parasite does not always attach itself to the back of its 

 host, J have a specimen of Temora longicornis with the 



