THE EUROPEAN SEAS. 



243 



dredge, we found an "uniform bottom of fine sedi- 

 ment in the form of yellow mud, inhabited through 

 great part by an uniform assemblage of marine 

 animals, mostly delicate, fragile, and colourless forms, 

 which became fewer and fewer both as to numbers 

 and individuals, and number of species, as the sea 

 became deeper and deeper." 



"Beds accumulating around the bases of rocky 

 submarine peaks, rising in deep water at a distance 

 from land, are more likely to be embedded with or- 

 ganic remains, than such as are formed along shore. 

 Round their bases will accumulate beds of shells 

 and corals, belonging to various zones of depth. 

 Such is the case, as we found by dredging, round the 

 peak of rock in the neighbourhood of Cape Artemi- 

 sium." 



The distribution in depth of the molluscous and 

 other forms, which were observed by Ed. Forbes in 

 the iEgean, has been already noticed ; that of the 

 Testacea of our own seas is given for every species 

 in the joint work of the same author and Mr. 

 Hanley.* 



Ed. Forbes thus subdivides the uppermost, or 

 littoral zone. First, a line with the smaller varie- 

 ties of Littorina rudis and L. neritoides ; a second, 

 with Mytilus edulis and larger forms of L. rudis; 

 a third, with Littorina littorea and Purpura lapillus ; 

 the lowest, with Littorina littoralis, Rissoa parva, 

 and Trochus cinerarius, accompanied on our west 

 * A History of British Mollusca. 



