III.] INTRODUCTION. xlix 



tacea," observed that, " in our own seas, Testacea, taken 

 from below 100 fathoms, even when they were indivi- 

 duals of species vividly striped or banded in shallower 

 zones, were quite white or colourless ; that between 60 

 and 80 fathoms striping and banding were rarely pre- 

 sented by our own shells, especially in the northern 

 provinces ; but from 50 fathoms shallow-wards, colours 

 and patterns were well marked." 



I cannot help thinking that there must have been 

 some mistake as to the first and second of these obser- 

 vations. At least, my own experience induces me to 

 form a different conclusion. 



Instances of depths exceeding 100 fathoms in our seas 

 are very rare. I only know of two. One of them is 

 a submarine trough off the Mull of Galloway, called 

 " Beaufort's Dyke," where the depth is 145 fathoms ; and 

 the other is a pit in the Sound or Sleat of Skye. The 

 results of dredging in Beaufort's Dyke are recorded in 

 the ' Annals of Natural History*.' Although shells 

 usually inhabiting comparatively shallow water, and 

 distinctly striped or banded (Tapes virginea and Venus 

 ovata), were obtained alive from this remarkable depth, 

 no deficiency of colour or markings is noticed in the 

 account of these results. In the other case, I can state 

 from my own knowledge that the shells were as highly 

 coloured and the markings quite as vivid as in specimens 

 found at a depth of 30 fathoms in another part of the 

 Sleat of Skye. Soundings were taken with Massey's 

 patent log, and living Testacea were brought up in the 

 dredge from 118 fathoms. On this occasion Captain 

 Otter was with me, and I had the benefit of his great ex- 

 perience in such matters. Last year I dredged for some 

 weeks off the Shetland Isles at depths between 60 and 



* Vol. x., Sept. 1842, p. 21. 



