SAXICAVA. 145 



south ; the reverse of which is the case with the next spe- 

 cies. It is found sometimes imbedded in stones or oki 

 shells, as oysters ; sometimes and very commonly attached 

 by a slight byssus to corallines, especially Sertulai'ite. and 

 AntennulariiE, also in the meshes of intertwining Serpulce, 

 especially in the complicated interlacements of the curious 

 Filopora filograna, and in the interstices of marine plants, 

 such as the coral-like NuUipore and the roots of Laminaria 

 digitata. It ranges from low water mark to very great 

 depths, and appears to prefer gravelly ground. Though 

 found almost every where on our coasts, when conditions 

 are favourable, and consequently enumerated in all our 

 local Faunas, a few localities may be specified in illustration 

 of its habits and range. In the south of England it occurs 

 boring into hard limestone at Plymouth (Montagu), and 

 red sandstone at Exmouth (Clark); free in twenty fathoms 

 water off the Land's End (R. M 'Andrew and E. F.) ; in 

 seven fathoms, stony ground, Weymouth (M 'Andrew) ; 

 Swansea (Jeffreys) ; Anglesea (Eyton) ; in twenty-five 

 fathoms, eight miles from land, north of Anglesea (M'An- 

 drew) ; on shell bank, twenty fathoms, north of the Isle of 

 Man, and twelve fathoms south (E. F.). Dead valves in 

 from one hundred and ten to one hundred and forty fathoms, 

 off the Mull of Galloway (Capt. Beechey, R.N.); all round 

 Ireland (Thompson) ; everywhere in the Hebrides ; in 

 fifty fathoms, five miles from land, off Cape Wrath (M' 

 Andrew) ; in crevices of stones, fifty fathoms on the high 

 banks, and alive in eighty fathoms off the west coast of 

 Zetland (M'Andrew and E. F.) ; dead valves in one hun- 

 dred fathoms, twenty-five miles from land off the east coast 

 of Zetland (M'Andrew). This species ranges throughout 

 the boreal and arctic provinces of the North Atlantic. It 

 is found rarely and of small size in the Mediterranean. 



