A STUDY OF A CRUSTACEAN. 57 



The only other wader coming to my notice was the Oyster- 

 catcher (H&matopus ostralegus), a common bird in this part of 

 England. On August 14th a flock that I estimated to contain 

 sis hundred birds came up the river, and we saw two other large 

 bodies join the first one. Altogether there must have been not 

 less than a thousand birds — more, one thought, than could have 

 been hatched in the whole of England. After performing a 

 number of striking aerial evolutions they vanished over More- 

 cambe Bay, and we saw them no more. The regular "garrison" 

 of my square mile consisted of about eight Oystercatchers. 

 These were very tame, coming to within a few feet of the garden, 

 and sometimes I saw one prod the dry sand with its bill, 

 obviously in search of Corophium ; but after perhaps a score of 

 thrusts the bird would return to the pool. The marks of the 

 bill on the level surface were visible from a distance of many 

 yards. 



From my observations I conclude that in Westmorland at 

 least this particular crustacean is quite well protected from 

 waders. Corophium is described by Quatrefages as a migrant on 

 the coast of France, appearing in swarms in April, and vanishing 

 suddenly in October — in a single night, he states. On November 

 7th Mr. Kershaw wrote from Sandside : — " Corophium now very 

 scarce, and I dug in a dozen places before finding any. Towards 

 the mouth of the estuary they seem commoner. Some of the 

 burrows now go down for five or six inches " ; and in December 

 they were still present in small numbers. For the present I 

 would suggest not migration but hybernation, either by means 

 of eggs or fertile females, and a seasonal summer abundance, as 

 in the case of so many invertebrates. But clearly there is much 

 to be learnt about the species. Indeed, in Spence Bates's work 

 on the ' Amphipoda' (p. 281), the author cannot even be certain 

 that Corophium makes its own burrows. I can decide this, for 

 those I kept in an aquarium burrowed at once, and in due course 

 formed the tubular prolongations of the mouths of the galleries 

 which I have already described. A number of crustaceans were 

 dissected, and cleared for microscopical examination, but without 

 any success in ascertaining their food. 



As the summer advanced, ducks in increasing numbers used 

 the sands as a diurnal resting place. The majority were Mallard 



Zool. 4th ser. vol. XVIII., February, 1914. F 



