1911.] 215 



oil the coat of a younjj friend of iiiiiie in his house at that place, the day after 

 he had walked beneath some burnt i3ines a few miles from the town. C. ferus 

 therefore seems to be spreading in Surrey, as it was also taken (singly) in a 

 fresh locality in the Woking district on August 7th. It has almost disappeared 

 from its old habitat at Horsell, a single example only having been taken as yet 

 this season, on August 8th. I have myself found it either on my coat or about 

 the house after arriving home from a walk in the pine-woods, showing that 

 the beetle possesses extraordinary clinging powers. — Id. 



The habitat of Eristalis xneus, Scoi). — At the northern end of Constantine 

 Bay, St. Merryn, Cornwall, the shore consists of shelving layers of contorted 

 slate sloping down from a height of about 15 feet. These shelves contain many 

 rock pools of different sizes, most of which at different periods are filled by the 

 sea. Those high up are rarely filled and either dry vip completely or are sup- 

 plied with fresh water from small springs ; those a little lower down get filled 

 only at the high spring tides (which have an amplitude of some 30 feet), and 

 even then only if those tides coincide witli a ground sea. Every gradation 

 exists down to pools filled every tide. On examining the spot about June 19th, 

 I noticed the presence of rat-tailed larvaj in some of the pools that are only filled 

 at the spring tides. The dimples formed by their tails were about one per two 

 square inches, and covered several square feet, so that there was quite a large 

 colony. It appeared that some weeks before there had been a heavy sea that 

 filled these pools with sea-wrack and weed, which was subsequently covered up 

 to a great extent with sand. The hot weather that followed caused active 

 decomposition to set in, so that the pools became filled with the rotting debris 

 and a sort of evil smelling " soup." Some of the pools were tinged deep red 

 with the colour extracted from the weed, and were full of various larvae, such 

 as Chironomus and Fucomyia. In certain somewhat shallower pools the Eris- 

 talis larvas were found, their bodies being in the rotting weed at the bottom, or 

 more rarely buried in the sand l^elow, with the tube only showing. 



Normally the situation is such that the high spring tide sweeps out the 

 pools, but the previous springs had been accompanied by exceptionally smooth 

 seas, so that they did not distiu-b the pools, and hence the favourable conditions 

 lasted longer than usual. The spring tides of June 26th were accompanied by 

 a moderate ground sea, and the pools were mostly swept by the waves, so that 

 a great many of the larvas were destroyed. On the return of the neaps the 

 conditions quickly reverted to their former state, but there r.nnained but one 

 small colony of Eristalis, and that in a fairly sheltered nook in one of the pools. 

 This colony was progressing well when I left on July 13th, and the perfect 

 insect was flying about the site. 



The habitat is such that the pools are exposed for many consecutive days 

 to the hot sun without any chance of replenishment of the water, so that the 

 salinity must vary considerably, and this is apparently without harm to the 

 larvae. Aboiit June 22nd several larvae were taken from the pool and placed in 

 glass vessel containing water and weed from the pool ; this vessel was placed 

 in a tray with a few inches of sand in it, and a strip of slate was placed in the 



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