51 



Dybder imellem 1000 og 2500 Favne. Hvad der imidlertid 

 ved denne Anledning er blevet kaldt "Globigerina-Ooze", 

 omfatter kun de Slamarter, som for en væsentlig Del be- 

 staar af hine Poraminiferer og altsaa har en meget høi 

 Kalkgehalt. Biloculinleret indebolder derimod paa mange 

 Steder - saaledes som de senere Analyser vil vise — kun 

 en ringe Mængde Kalkskaller i Forhold til sine øvrige 

 mineralske Bestanddele. Lerets Forraad paa Globigeriner 

 differerer nemlig meget i de forskjellige Dele af Nordhavet. 

 Biloculinerne synes derimod at være temmelig jevnt fordelte 

 over Havbnnden. men da de i Almindelighed forekommer i 

 ringe Antal (sjelden ser man mere end 2 Biloculiner paa 

 en Kvadratcentimeter af den tørrede Bundprøve) kan de 

 ikke i nogen betydelig Grad bidrage til Lei-ets Kalkgehalt. 

 Paa Grand af disse Dyrs regelmæssige Forekomst og Ud- 

 bredelse i Dybvandsslammet synes det mig. at Navnet 

 "Biloculinler" er heldig valgt. 



For at kunne gjøre os en Ide om. hvilken Betydning 

 hine Foraminiferer har for Dannelsen af de Afleiringer. i 

 hvilke de forekommer, maa vi tåge deres zoologiske Forhold 

 i Betragtning. 



Med Hensyn til Globigerinerne er Zoologerne i Uenig- 

 bed om. hvorvidt de blot er pelagiske Dyr. eller om de 

 også a formaar at leve paa BTavbunden 1 . De bekj endte bri- 

 tiske Naturforskere Sir Wyville Thomson. Jeffreys og John 

 Murray er af den Mening, at Globigerinerne blot lever som 

 fritsvømmende Dyr i Havet, og at de først efter sin Død 

 synker tilbunds. Dr. Carpenter forfægter imidlertid en 

 anden Anskuelse, hvori ogsaa Prof. Sårs er enig med ham, 

 nemlig at Globigerinerne i sin første Levetid er pelagiske, 

 men tilbringer den sidste Del af sin Tilværelse paa Hav- 

 bunden. 



De øvrige i Slammet forekommende Foraminiferer 

 har man ikke fundet i de øvreliggende Yandlag. og de synes 

 derfor at være henviste til blot at leve paa Bunden. Blandt 

 de almindeligste af disse maa nævnes Slægten Lituola med 

 kuglerunde. af Jernfosfat bruntfarvede Skaller, og Nonionina, 

 hvis uorganiske Del bestaar af ren kulsur Kalk. Forovrigt 

 tindes der i Leret ogsaa andre Foraminiferer. der danner 

 sine Skaller paa væsentlig mekanisk Vis ved Sammenkitning 

 af Lerets forskjellige Partikler. 



Levninger af kiselpantsrede Dyr er ikke synderlig 

 udbredte i Biloculinleret. Under Mikroskopet ser man i 

 de fleste Prover enkelte smaa tine Spikuler af Svampe, 

 men disse forekommer dog i meget større Maalestok i 



1 Med Hensyn til den zoologiske Literatur om dette Emne kan 

 nævnes foldende Afkandlinirer: Dr. AVallich : "The North-Atlantic sea- 

 bed." Preliminary Report by Dr. Carpenter. iFrom the Proeeedincrs 

 of the Royal Society No. 107, 1'868). "Deep-séa exploration," a lec- 

 ture by J. Grwyn Jeffreys. 



Expedition. having been met with almost everywhere in 

 depths ranging from 1000 to 2500 fathoms. Meanwhile. 

 the surface-layers to whicb the name of "globigerina ooze" 

 • has been given by British naturalists, comprises only such 

 deposits as consist in great part of those Foraminifera and 

 are accordingly distinguished by a very large proportion of 

 lime. Biloculina clay. on the other hand. contains in many 

 localities — as will appear from the results of analyses 

 subsequently given — very few calcareous sbells compared 

 to its other mineral constituents. Tbns. the number of 

 Gldbigerinæ in this clay from the different parts of the 

 North Atlantic varies considerably. whereas the distribution 

 of Biloculinæ would appear to be comparatively uniform; 

 but these animals occurring as a rule sparingly (more than 

 2 Biloculinæ are seldom observed to a square centimetre 

 of dried deposit). they cannot of course materially contri- 

 bute to the proportion of lime in the clay. The uniformity 

 of occurrence cbaracterising the distribution of these ani- 

 mals throughout the deep-sea deposit of the North Atlan- 

 tic, naturally suggested "Biloculina clay" as an appro- 

 priate name. 



To form a just idea of the extent to which these 

 Foraminifera contribute to the formation of the deposits in 

 which they oceur. \ve must also investigate their zoological 

 conditious. 



With regard to Gldbigerinæ, zdologists do not agree. 

 some regarding those Foraminifera as strictly pelagic and 

 otbers as animals whose habitat is the bed of the sea. 1 

 The British naturalists Sir Wyville Thomson. J. Gwyn 

 Jeffreys. and John Murray, are of opinion that Globigerinæ 

 during life swini freely in the waters of the ocean and when 

 dead sink to the bottom. Dr. Carpenter entertains a diffe- 

 rent view. shared by Professor G. O. Sårs. according to 

 which Globigerinæ are pelagic during the early stages ol 

 their existence but pass the remainder on the sea-bed. 



The other species of Foraminifera present in deep-sea 

 deposit have not "been met with in the upper strata of the 

 ocean, and would appear therefore exclusively to inhabit 

 the bottom. Of these animals the genera most riumerously 

 represented are Lituola, with glolmlar shells. brown in 

 colour from the phosphate of iron they contain, and Nonionina, 

 of which the inorganic part consists of pure carbonate of 

 lime. For the rest. North-Atlantic deposit contains divers 

 other Foraminifera, whicb build up their shells in greater 

 part mechanically. by cementing together minute particles 

 of the clay. 



Siliceous remains of animals are not particularly abun- 

 dant in Biloculina clay. Examined under the microscope, 

 most of the samples were found to contain delicate spicules 

 of sponges. but such constituents occur in far greater num- 



1 The following are some of the chief works in which this 

 subject is treated: — .Dr. Wallich: "The North-Atlantic Sea-Bed;" 

 "Preliminary Report by Dr. Carpenter (From the Proceedings of the 

 Royal Society, No. 107. 1868). -Deep-sea Exploration," a Lecture by 

 ,T. Gwyn Jeffreys. 



