242 



NATURE OF SEA-BED. 



to me in the Mediterranean : and of the last divi- 

 sion, or 6 glacial' species, I detected three, Nucula 

 decussata, Neaera cuspidata, and Cardium suecicum. 

 Philippi has given Area raridentata as Sicilian." 



Mr. Jeffreys found that more than thirty species, 

 which had been supposed to be restricted to our 

 British seas, ranged into the Mediterranean. 



The relation of the nature of the sea-bed and the 

 associated Testacea to depth of water, was carefully 

 observed by Ed. Forbes and the officers of the 

 Beacon. For more than two months the dredge 

 and the sounding-lead were actively employed for 

 this purpose, in the Gulf of Macri, on the Lycian 

 coast. 



" Tracts of sand are forming near the shore, and 

 off the mouths of the larger rivers. This is espe- 

 cially the case on exposed coasts, as in the instance 

 of that part of the Lycian shore where the Xanthus 

 empties itself into the sea. There the sea is shallow 

 for some distance, and for a considerable breadth, 

 the bottom being formed of a tract of sand. Such 

 a bottom is not favourable to abundance or variety 

 of marine life, and Testacea are by no means plenti- 

 ful in such places. 



" The muddy deposit from the deep sea 'is usually, 

 almost invariably, of a pale yellow colour, and, when 

 dried, nearly white. The region of this yellow mud 

 is the sea-bed below eighty fathoms, more commonly 

 below one hundred. From that depth down to as 

 deep as we were able to explore by means of the 



