Nest of a Mo Husk. 175 



" for which I am indebted to the kindness of Mr. D. 

 Robertson, I have been able to learn the nature and 

 object of this membrane," and after a discussion of it 

 he adds that, from various observations as well as 

 from information supplied by Mr. Robertson, it 

 appears " manifest that the membrane is a provision 

 for the support of the growing Adamsia, when it has 

 selected small or broken shells." 



Still more interesting are the observations which 

 Robertson supplied to Gwyn Jeffreys, for use in the 

 "British Conchology," published in 1863, on the 

 habits of Lima hians, a marine shell-fish allied to 

 the pectens : 



" In confinement they build freely ; and so far as 

 my observations go, they live longer in that state 

 when they are supplied with the requisite materials, 

 but failing such supply they frequently make nests of 

 their own byssus. They also spin their byssal threads 

 to assist them in ascending perpendicular or steep 

 places ; and like the common mussel, the Lima often 

 suspends itself by one or more fibres. Its attachment, 

 however, is only slight ; for the least irritation or 

 alarm causes it to detach itself from the cable and 

 bound off. It does not seem to be particular as to the 

 kind of building-material which it uses. At Loch- 

 ranza in Arran I found their nests among the muddy 

 roots of Phyllophora rubens, without the addition of 

 any harder substance. At Rothesay the nests are 

 made of small gravel ; and at Cumbrae they soon fill 

 the dredge, being formed of thick and matted clusters 

 of nullipore. On this bank I never find them free, 

 they are all encased, at all seasons of the year, young 



