8o DISCOVERY REPORTS 



ii8. Ammobaculites bargmanni, sp.n. (Plate II, figs. 23-6). 

 Five stations: 27, 45, 123, 144, 148. 



Test large, free, planispiral, involute; consisting of about three convolutions of 

 chambers rapidly increasing in size and thickness. Umbilical area much depressed; 

 seven to nine chambers in final convolution, the last chamber, or at most the last two 

 chambers, becoming extended into a straight growth bearing the terminal aperture, a 

 large elongate slit. Sutures depressed, peripheral edge sub-acute, becoming rounded in 

 the final chambers. Surface smooth but unpolished, generally composed of very fine 

 sand grains, neatly and firmly bound together without visible cement. Coarser grains 

 are sometimes used, giving a rough exterior to the test. Walls thin, rough internally. 

 Colour grey, the umbilical portion sometimes brown. Size, up to 3-5 mm. in diameter, 

 sometimes even larger. 



Young individuals appear to be inseparable from the young of A. americanus, except 

 for the slightly depressed sutural lines. There is a tendency to abandon the usual neatness 

 of construction in the final stages, the last chamber or two often having a few very large 

 sand grains incorporated in the walls. 



A. bargtnamii appears to be a very distinctive species, linking the genera Haplo- 

 phragmoides and Ammobaailites, and so perhaps demonstrating the zoological continuity 

 of the group, and the futility of their separation. Up to the time of the formation of the 

 last two or three chambers, the test is a typical Haplophragmoides, its nearest ally being 

 apparently H. compressiim (Goes) (= H. ernaciatum, Brady) (G. 1882, RRCS, p. 141, 

 pi. xii, figs. 421-3 ; 1896, DOA, p. 31). With the formation of these final chambers, it 

 assumes the external characteristics of Ammobaadites, and bears some resemblance to 

 A. americanus, from which, however, it is easily separable owing to its involute con- 

 struction, depressed sutures, inflated chambers, and its size, which is nearly double that 

 of A. americanus. It appears to be one of the largest recorded species in either genus. 



A. bargmanni is not infrequent at a depth of 270 m. at St. 45, which is at the entrance 

 to Cumberland Bay; it is rarer at the lesser depths of other adjacent stations. The 

 species appears, therefore, to be confined to a very limited area. At Sts. 27 and 148, 

 coarser material is employed for construction of the test than at the remaining stations, 

 with the result that the specimens have a very rough and untidy appearance. At St. 144, 

 both smooth and rough-walled specimens were noted. 



The species is named after H. E. Bargmann, Ph.D., of the Discovery Staff, who has 

 assisted me in the preparation of index, charts, etc. 



119. Ammobaculites rostratus, Heron-Allen and Earland (Plate V, figs. 22-5). 



Ammobaculites rostratus, Heron-Allen and Earland, 1929, etc., FSA, 1929, p. 328, pi. ii, figs. 

 14-17. 



Fourteen stations: 27, 41, 45, 123, 126, 143, 149, 660; WS 28, 32, 40, 42, 63-4; MS 68. 



Test free, thin-walled and rather fragile, compressed, piano-spiral and evolute. 

 Consisting of two to three convolutions, with from five to seven chambers in the last con- 



