20 BULLETIN 104, UNITED STATES NATIONAL MUSEUM 



DISCORBIS CHASTERI (Heron-Allen and Earland) 



Plate 4, figures 1-4 



Discorbina minuiissima Chaster (not Seguenza), First Rept. Southport Soc. 

 Nat. Sci., 1890-91 (1892), p. 65, pi. 1, fig. 15. 



Discorbina chasteri Heron-Allen and Earland, Proc. Roy. Irish Acad., 

 vol. 31, pt. 64, 1913, p. 128, pi. 13, figs. 1-3; Trans. Linn. Soc. London, 

 ser. 2, vol. 11, 1916, p. 272; Journ. Roy. Micr. Soc, 1916, p. 50. 



Discorbis chasteri — Material examined 



Test minute, subglobiilar, periphery broadly rounded, circular or 

 oval in outline, last-formed whorl typically of but four chambers, 

 inflated; sutures very distinct, somewhat depressed, those on the 

 dorsal side curved, on the ventral side nearly radial; wall very smooth, 

 very finely perforate, the v/all appearing clear and transparent, on 

 the umbilical side with fine lines radiating from the open umbilicus; 

 aperture opening into the umbilical cavity. 



Diameter 0.08-0.14 mm.; breadth 0.05-0.08 mm. 



This small but distinctive species occurs about the British Isles, 

 and I have a very fine set of them from Goldseeker Station 16 off 

 Faroe Islands, 62° N.; 6° 12' W. in 128 meters, kindly sent me by 

 Earland. Two of these are drawn on our plate as well as a copy of 

 the original figures. The species has been recorded also by the original 

 authors from the Kerimba Archipelago off the southeastern coast of 

 Africa, and from the Antarctic, a very unusual distribution if these 

 are really all the same. 



DISCORBIS CHASTERI (Heron-Allen and Earland), var. BISPINOSA (Heron-AIIen and Earland) 



Plate 4, figures 5, 6 



Discorbina chasteri Heron-Allen and Earland, var. bispinosa Heron- 

 Allen and Earland, Proc. Roy. Irish Acad., vol. 31, pt. 64, 1913, p. 129, 

 pi. 13, fig. 4; Trans. Linn. Soc. London, ser. 2, vol. 11, 1916, p. 273; Journ. 

 Roy. Micr. Soc, 1916, p. 50. 



Variety differing from the typical in the development of spines 

 from the periphery of the chambers, progressively increasing in 

 number from one to three. 



Specimens of this interesting variety are in my collection through 

 the kindness of Earland. They are from Goldseeker Station 16, with 

 the typical. Some of the specimens show the progressive develop- 



