FOKAMINIFERA OF THE ATLANTIC OCEAN 15 



This species was originally described by d'Orbigny from the coasts 

 of Cuba and Martinique, and I have recorded it from Porto Rico, 

 Jamaica, and from the Tortugas off the coast of Florida. It seems 

 to be a rare form, although well distributed in the West Indian region. 



DISCORBIS BACCATA (Heron-Allen and Eailand) 



Plate 3, figures 1 a-c 



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

 vol. 31, pt. 64, 1913, p. 124, pi. 12, figs. 1-3; Trans. Linn. Soc. London, 

 ser. 2, vol. 11, 1916, p. 271; Journ. Roy. Micr. Soc, 1916, p. 50; 1930, 

 p. 183. 



"Test free, circular or nearly so in outline, peripheral edge sub- 

 acute, consisting of about three convolutions, the last convolution 

 having seven to nine oblique chambers ; superior face conical, rounded 

 at the apex; inferior face almost fiat, the central region filled with 

 a raised star-like stud of solid shell matter, the short points of the 

 star directed toward the sutural lines, which are somewhat depressed 

 on the base, but flush and hardly recognizable on the superior side 

 of the shell. The surface of the chambers on the inferior side slopes 

 downward toward the centre, so that the top of the star-like stud 

 is about on the same level as or slightly raised above the peripheral 

 edge. 



"The entire surface of the shell is shagreened or densely covered 

 with minute beads, between which are the pseudopodial perforations. 

 On the superior or conical side of the test these beads are not very 

 noticeable except under a % or ^ inch objective, although their 

 presence gives a characteristic roughness to the surface of the shell. 

 On the base, however, they attain much larger dimensions, and are 

 arranged regularly in radial lines. 



"In li^^ng specimens the shell is polished and of a dull yellowish 

 translucent tint. After death, however, it becomes white and opaque, 

 and appears to be subject to rapid decomposition, the surface becom- 

 ing rough and eroded. This appears to be commonly the case with 

 Foraminifera in which the surface is covered with exogenous bead 

 growth, e. g. Discorbina parisiensis, D. wrightii, etc. 



"Discorbina baccata belongs to the D. rosacea group, and occupies 

 a position about midway between Discorbina (Asterigerina) rosacea 

 d'Orbigny, Asterigerina planorbis d'Orbigny, and Discorbina (Tro- 

 chiilina) turbo d'Orbigny. It resembles the last form most closely in 

 its flattened base, but differs in its sunken septal lines on the basal 

 surface and in its characteristic basal stud and beaded surface. 



"Breadth, 0.3-0.4 mm.; height, 0.2 mm. Beads average about 

 0.008 mm. Diameter of umbilical star about 0.1 mm. 



"The species is fairly common in the dredging from Inishgowla 

 harbour (Station 13) and in other gatherings among the islands. 



