Il6 GEOLOGICAL BLOLOGY. 



Marine Organisms Particularly Important to the Paleontologist. 

 — Because of the fact that preservation of fossils is almost 

 entirely dependent upon the covering by water of the remains 

 preserved, the questions of distribution and environment of 

 chief interest to the paleontologists are those of marine and 

 fresh waters. 



Haeckel's Classification of the Marine Conditions of Life. — 

 Walther, in his " Bionomy of the Sea," presents a classifica- 

 tion of organisms according to their bionomic character, as 

 follows: The sum of the marine faunas and floras is called 

 Halobios, corresponding to them the fresh-water life is called 

 Limnobios, and the land organisms receive the name Geobios. 

 The Halobios, or marine organisms, are further classified 

 into (i) Benthos — those animals and plants living on the 

 sea-bottom, distinguished further as {a) sessile, (b) vagile, 

 {c) littoral, and {d) abyssal Benthos; (2) Nekton, or the life of 

 open sea, with strong powers of active locomotion ; and (3) 

 Plankton, the more or less passive life of open seas. Haeckel 

 (from whom Walther adopts the nomenclature) further sub- 

 divides the Plankton, or open-sea life, into the following five 

 groups: The neritic Plankton includes the swimming flora 

 and fauna of the coast regions of continents, archipelagos, 

 and islands; the oceanic Plankton includes the swimming 

 flora and fauna whose habitat is the open ocean ; the pelagic 

 Plankton inhabits the ocean surface and approximately 200 

 metres below ; the bathybic Plankton inhabits the waters from 

 the bottom for about lOO metres up, and between the latter 

 two lives the zonaric Plankton.* 



Walther's Further Analysis of Conditions of Environment. — 

 Walther has amassed very interesting statistics to show the 

 particular influence upon distribution of the various condi- 

 tions of light, of temperature, of salinity, of tides and waves, 

 of currents and ocean circulation, and has classified the floras 

 and faunas of the seas in relation to these conditions. 



The flora of the shores, littoral flora, are divided into that 



of the (i) dune and sand-plain zone, (2) flora of coast rocks, 



(3) of the mud zone, (4) the sand-plants flora. Four different 



*Walther, " Einleitung in die Geologic als historische VVissenschaft, i. 

 Theil, Bionomic dcs Meeres," 1S73, pages 16-22; also Haeckel, " Plankton- 

 studicn," Jena, iSgo, page iS, etc. 



