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THE YOYAGE OF H.M.S. CHALLENGER. 
very rare and the specimens exceedingly small, so that material does not exist for more 
detailed investigation as to the chemical nature of the test ; nor is sufficient known of the 
condition of the sea-bottom in these cases, to account for any deviation from the normal 
type of structure. 
The best examples of Reophax membranacea hitherto obtained are from the South 
Atlantic, off the coast of South America, in about the same latitude as Buenos Ayres, 
1900 fathoms; but it occurs also in the deep area of the North Pacific, Station 238, 
depth 3950 fathoms. 
Reophax sabulosa, H. B. Brady (PI. XXXII. figs. 5, 6). 
Reophax rudis, Brady, 1881, Quart. Journ. Micr. Sci., vol. xxi., N. S., p. 49. 
„ „ Carpenter, 1881, “The Microscope,” 6th ed., p. 563, figs. a.h. 
„ sabulosa, Brady, 1882, Proe. Roy. Soc. Edin., vol. xi. p. 715. 
Test elongate, cylindrical, slightly tapering ; sides even and unconstricted, extremities 
rounded. Walls thick, composed of rather fine grey sand only partially cemented, and 
showing no external marks of segmentation. The longitudinal section reveals about six 
segments, each tapering at the summit to a stoloniferous tube, the mouth of which, as 
well as the external aperture of the test, is stained reddish-brown. Length, y%th inch 
(10 mm.) or more. 
This species was originally described in one of the preliminary notices of Challenger 
Foraminifera under the name Reophax rudis, hut it was subsequently found that the 
same specific term had been previously employed by Costa for another variety of the 
type, and the present name was therefore substituted for it. 
Reophax sabulosa furnishes some of the largest examples of the genus, the only 
variety attaining superior dimensions being Reophax nodulosa. Its thick and somewhat 
loosely constructed walls bear more resemblance to the investment of Astrorhiza arenaria 
than to the firmly agglutinated tests of its immediate congeners ; nevertheless its well- 
marked segmentation, and the manifest relationship of the species to such forms as Reophax 
cylindrica, the characters of which are more in harmony with the rest of the group, are 
sufficient evidence of its Lituoline affinity. The brown colouring of the septal apertures 
is a not uncommon feature of loose sandy tests deficient in cement, and appears to he 
due to an organic pigment. 
Reophax sabulosa has only been found in the cold area of the Faroe Channel, at 
depths of 530 and 540 fathoms. The original specimens, two of which form the 
subject of the figures in PI. XXXII., were obtained by Dr. Carpenter during the cruise 
of the “ Lightning” in 1868, and it has been taken more recently near the same spot on 
the cruise of the “ Knight Errant.” 
