Notices of Memoirs — Br. J. Murray — Marine Organisms. 227 



rare ; Krithe Bartonensis (Jones), very rare ; Cytherella Dixoni, Jones 

 and Sherborn, very rare; C. compressa (Miinster), rare; C. Beyrichi 

 (Reuss), rare; C. Beussi, Jones and Sherborn, rare. 



CcELENTERATA TurhinoUa humilis, Milne Edwards and Haime,^ 

 two specimens. 



FoRAMiNiFERA. MiUoUna trigonula (Lamarck), very rare ; 

 M. Schreibersii (D'Orbigny), very rare; HaplopJiragmium foliaceum, 

 Brady, rare ; PolymorpJiina gibba, D'Orbigny, very rare ; P. laden, 

 Walker and Jacob, very rare; Nummulites variolaria (Lamarck), 

 excessively common. 



L — Makink Organisms and the Conditions of their 

 Environment. By Dr. John Murray, F.R.S.^ 



THE ocean may be divided into two great biological regions, 

 namely, the superficial region, including the waters between 

 the surface and a depth of about 100 fathoms, and the deep-sea 

 region, extending from the 100 fathoms line down to the greatest 

 depths. The superficial region may be subdivided into two pro- 

 vinces, the shallow-water or neritic province around the land 

 masses where the depth is less than 100 fathoms, and the pelagic 

 province, embracing the superficial waters of the ocean basins 

 outside the 100 fathoms line; these two provinces contrast sharply 

 as regards physical conditions, which are of great variety in the 

 neritic province, and very uniform over wide areas in the pelagic 

 province. 



Temperature is a more important factor in determining the 

 distribution of marine organisms, mostly cold-blooded, than in the 

 case of terrestrial species, mostly warm-blooded and air-breathing 

 animals, the distribution of which depends rather upon topo- 

 graphical features than upon climatic conditions. 



The pelagic tropical waters of the ocean teem with various 

 forms of life, of which probably 70 to 80 per cent, are plants, 

 converting, under the influence of sunlight, the inorganic con- 

 stituents of sea- water into organic compounds, thus forming the 

 original source of food of marine animals both at the surface and 

 at the bottom of the sea. 



The number of species living in the pelagic waters of tlie tropics 

 may greatly exceed the number in polar waters, where, on the 

 other hand, there is often a great development of individuals, so 

 that there is probably a greater bulk of organic matter in the cold 

 polar waters than in the warm tropical waters. The rate of animal 

 metabolism is slower at a low than at a high temperature, and 

 organisms inhabiting tropical waters probably pass through their 

 life-history much more rapidly than similar organisms living in 

 polar regions. Carbonate-of-lime-secreting organisms are most 



1 Previously recorded from the Barton beds of Hampshire. 



2 An Addi-ess delivered at the Royal Institution. 



