ADAMS : HVDROBIA (PALUDESTRINAJ JENKINSI. 149 



go regularly to Countess Weir. Between 1840 and 1855 there 

 was a regular trade between St. Petersburg and Finland and 

 Topsham, in hemp, tar, and timber, which trade ceased with 

 Topsham thirteen years ago, the timber being now unshipped at 

 Exmouth and sent to Exeter by rail or canal. 



Sandwich, too, in former times, imported timber from 

 Cronstadt (whence timber from Finland may also have been 

 shipped), and also from several Swedish and Prussian ports, and 

 this trade was continued till quite recently, when the improved 

 harbours of Dover and Ramsgate killed it. 



Along the south bank of the Thames timber has been 

 unloaded from, doubtless, many parts of the world, but certainly 

 from Russia and Finland. 



The only ports, then, trading mutually with two of our 

 three EngUsh ports are Cronstadt (St. Petersburg) and some 

 Finnish ports along the Gulf of Bothnia. Though Topsham 

 imported timber also from America, I do not find that Sand- 

 wich ever did so ; Sandwich, again, imported timber from 

 Sweden, Norway, and Prussia, but I can find no record of the 

 same for Topsham. 



Now the fact of the same foreign locality exporting timber 

 to three different British ports (the only kncwn habitats of the 

 species in question), and that same foreign locality being the 

 only one, as far as my information goes, trading mutually with 

 two of the three seems a curious coincidence, and, though by 

 no means amounting to anything like proof, forms a provisional 

 hypothesis. 



This hypothesis would be greatly strengthened if the shell 

 were found in any other of our ports which trade or have traded 

 with Russia or Finland — e.g., Newhaven and Wisbech — where I 

 would suggest that search be made. 



And, lastly, it would vastly increase its probability if the 

 species were found to exist in some of the low-lying marshes 

 along the Russian or Finnish coasts. 



