Letter from Henry Denny to Sir John Richardson, relating to the getting of information about Arctic fauna This being indebted to him for his exertions on his behalf and also to Mr Rae through Richardson's influence, listing lice from migratory birds, nearly all of which are known to him, and asking whether he could induce some of the traders in the fur countries could get lice from quadropeds such as beaver, bear, Arctic fox, etc 5 Nov 1850