Natural HUlory and Physiology. 337 



antly with creatures of unquestionably Scandinavian and 

 Arctic parentage, not isolated or straggling, as those of simi- 

 lar character in the western provinces are, but seated at the 

 true bounds of the great boreal province which here inter- 

 sects the British Seas. The dredge has been used within 

 the area reported on in all depths between four and a hun- 

 dred fathoms. Everywhere do we find the distinction of 

 Littoral, Laminarian, and Coralline zones maintained, and in 

 the Scottish provinces, that deeper region to which Professor 

 E. Forbes had previously given the name of *' deep-sea 

 coral,'* on account of the numbers and abundance of calca- 

 reous, zoophytic and bryozoic polypedons procured from the 

 greater depths. Between the coasts of Cornwall and Ireland, 

 Mr MacAndrewhas dredged and carefully noted the MoUusca 

 inhabiting the region of fifty fathoms ; and it is very curious 

 and interesting to observe that only at such depths, and in 

 peculiar localities, in the southern part of the British Seas, 

 do we find those species of Scandinavian origin which give a 

 feature to even the shallower zones in the sea-beds of North 

 Britain. The tables now presented shew that whilst certain 

 species of marine creatures are absolutely restricted to de- 

 fined provinces of depth, those of the Littoral and Lamina- 

 rian zones, being especially limited in range, alter ; and not 

 a few have a power of enduring all the various conditions 

 between the coast line and 100 fathoms, but in every case of 

 wide range there is some portion in each region where the in- 

 dividual of each species attains a maximum in number. The 

 higher zones of our sea are distinguished by the presence of 

 peculiar genera as well as species, but in the lower zones, the 

 peculiarity is maintained almost entirely by peculiar species of 

 genera, which have a wide bathymetrical range. According to 

 the nature of the sea-bottom the proportion of species and of 

 individuals of particular tribes of Mollusca and Radiata is de- 

 termined. Among the former, the Acephalous species prevail 

 over the Paracephalous in proportion to the more sandy or 

 muddy character of the soundings, whilst the latter equal or 

 exceed the former when the bottom is of muUipore, or hard, or 

 abounding in stones of any size. A comparison of the species 

 of Mollusca and Radiata, in the several provinces before 



V^OL. XLIX. NO. XCVIII.-^OCTOBER 1850. V 



