190 "TERRA NOVA ■ EXPEDITION. 



that it extends eqiiall)' far to the south, and that in the most southerly hititudes it 

 is more or less replaced by G. pachyderma, as in the Arctic Seas. 



Dr. Harvey Pirie, in his Memoir on " The Deep Sea Deposits of the Scottish 

 National Antarctic Expedition " (P., 1913, SNA.), records the presence of the two 

 forms together in many of the deposits examined by him. 



G. dutertrei becomes the dominant type at Station 1(3. where the Foramini- 

 fera in the material consisted of 9.3 per cent, of this species ; and at Stations 17, 18 

 and 20 at least 99 per cent, of the whole material as dredged. South of these 

 Stations the nature of the material becomes normally varied, with a correspond- 

 ing decrease in the number of the (41obigerinae. 



Universally distributed, but in the N.Z. area rare, except at Station 9, where 

 many very good examples were found. In the deep water those soundings, 

 which were Glohigerina oozes, consisted almost entirely of this species, as recorded 

 above. In the Antarctic coastal area the Globigerinae naturally form a smaller 

 percentage, but G. dutertrei retains its dominant position among the Globigerinae, 

 becoming more thick-shelled, starved and approximating by imperceptible degrees 

 to G. parhydernm. until at many Stations it is difficult to draw a line by which 

 the specimens of the species can be separated from the other. Well-marked indi- 

 viduals of G. dutertrei, however, occur everywhere and particularly at Stations 36, 

 38 and 53. At tlie dominant Stations large numbers of abnormal and wild- 

 growing specimens occur, ranging between double individuals inseparable from 

 G. helicina, to " sports "" in which individual chambers are malformed and tubular, 

 in fact the species seems more subject to these biological malformations than 

 any other Globigerinae. Many of the benthic specimens also exhibit excessive 

 thickening of the shell-wall by the deposition of concentric layers of calcium 

 carbonate. Such thickening, by obliterating the sutural depressions, brings the 

 smaller specimens into practical identity with G. pachyderma when the oral 

 aperture is of a depressed character. 



Kiaer (K., 1899, NNAE, pi. i. fig. 7) figures similar .specimens with tulnihir out- 

 growths as " Globigerina sp." from the Arctic Seas. 



[Arenaceous isomorph, Haplophragmium globigeriniforme, P. & J.] 



479. Globigerina pachyderma (Ehrenberg). 



Aristerospira j)acliyderma. Ehreuberg. 1873, LMT. p. 386, pi. i, fig. 4. 



„ crasm, Ehrenberg, ibid, p. 388, pi. iii, fig. 9. 



Globigerina omphalotetras, Ehrenberg, ibid, p. 388, pi. iii, fig. 11. 



bulloides, Brady, 1878, RRNP (• Arctic variety "") p. 4.3.5, pi. x.xi. fig. 10. 



var. borealis, Brady, 1882, FKE. p. 716, 717. 

 2Kichyderma, Brady, 1884, p. 600, pi. cxiv, figs. 19, 20. 



„ Murray and Renard, 1891, Chall. Rep. " Deep Sea Deposits.'' p. 260. 



pi. XXV, fig. 12. 

 Heron-Allen and Earland, 1908. etc., SB 1909, p. 438. pi. xviii. figs. 4. 5. 

 Pearcey, 1914, SNA. p. 1,024 (c). 



