264 The Naturalist of Cumbrac. 



preservation ; even some of the tender CallitlLarnnions 

 appeared quite as good as if they had been mounted 

 when newly taken from the water ; but I may mention 

 that Wrangelia multifida was a little brownish and 

 Dasya coccinea a little more intensely red. 



" The crustacea were all in fine order when taken 

 out of the salt at eight days' end, and I believe would 

 have kept so for a twelvemonth. 



" It would be no slight recommendation for the 

 salt, had it none other than the convenience it affords 

 in carrying these things home in a dry state, avoiding 

 the risk of breaking the vessels with spirits. But a 

 greater advantage is derived from the use of salt in 

 applying it to the peaty mud found at the bottom 

 of lakes, not especially for the preservation of the 

 animals found in the mud, but for the solubility it 

 gives to the peat when put in water, causing it to 

 sink after being dried, and allowing shells, etc., to float ; 

 whereas, without the salt, the whole peaty mass will 

 neither dissolve nor sink in such a way as to allow 

 shells, ostracoda, and the like, to be separated con- 

 veniently from the floating peat." 



Later in the year Mr. Robertson paid his friend 

 Dr. Brady a visit at Sunderland, the two as usual 

 examining the rocks, dredging in the sea, and scour- 

 ing the pools of the neighbourhood for specimens. 

 When apart they often had to interchange objects of 

 natural history through the post. In a letter to Brady 

 dated October 18, 1871, Robertson says, "The box 

 was well enough packed under all ordinary circum- 

 stances, but I do not think that the post-office officials 

 like parcels, and I believe, from the effects that we 



