34 "TERRA NOVA" EXPEDTTTOX. 



iudistiuguisliable in the superior aspect from G. hulloides), it is known to be a 

 pelagic species and is doubtless of world-wide distribution. 



The replacement of the comparatively thin-walled Globigerinae of warm seas 

 by thicker-walled types, like G. dutertrei and G. pachtjderma, as one approaches 

 the poles, is a very remarkable fact and at variance with the general rule that 

 organisms secrete calcium carbonate in greater abundance under tropical condi- 

 tions than under arctic. It might be expected that their arenaceous isomorphs 

 would increase in abundance. But the arenaceous isomorph of Globifjerina 

 {Hap/opJiraf/miii7n glohigeriniforme) is not more prevalent ui the Arctic and 

 Antarctic than elsewhere. Vide our previous reference to this subject on p. 27. 



Incidentally, the records of G. faclnjderma in Brady's list (B. 1884, F.C. 

 p. 784) are puzzling in the extreme. He records it at four out of the six Arctic 

 stations Init at none of the Antarctic, and in his description of the form (B. 1884, 

 F.C. p. 600) he does not refer to its occurrence at any point south of the Faroe 

 Channel. Yet he, of all men, must have been thoroughly familiar with the 

 type, for he rediscovered the species, which had been described in 1861 and figured 

 in 1873 by Ehrenberg, and then forgotten. The only explanation possible seems to 

 he that some of Brady's assistants who worked out the Antarctic material for him 

 overlooked the extreme " pachyderma " type and selected the starved "dutertrei" 

 specimens mstead. G. pachyderma can hardly have been lacking at "Challenger" 

 Station 150. 



(iv) PELAC4IC FOEAailNIFEEA. 



Eighteen tubes of tow-nettings taken by the Terra Nova were placed in our 

 hands for examination. They covered the whole period of the voyage, four being 

 from Stations in the Atlantic on the outward cruise, five from the seas round 

 the extreme north end of New Zealand, and the remaining nine being spread 

 over the area between the South Island of New Zealand and the Antarctic 

 coast-line. Eight of the stations yielded pelagic Foraminifera, but as three of 

 these were from the warm Atlantic, and four from warm New Zealand seas, 

 they present little interest for this report. The eighth and most southerly 

 tow-netting in which pelagic Foraminifera were detected was from Station (Off.) 167. 



Unfortunately, all the material had been preserved in formalm, than which as 

 we have observed (ante), no more unsatisfactory mediimi for pelagic Forammifera can 

 be conceived. As a result all trace of the thin calcareous shells had vanished and 

 nothing was left but the protoplasmic bodies of the animals held together by 

 the delicate chitinous linmg of the original shell. Identification of species has 

 therefore been confined to those forms in which the shape and method of 

 arrangement of the chambers is sufficiently distuictive for recognition. Probably 

 pelagic forms had been present in most of the other gatherings, but had become 

 too much destroyed for recognition. The incident is the more unfortunate as 



