138 PROCEEDINGS OF THE NATIONAL MUSEUM vol.77 



marl of Cooper River, S. C. and in a pit on the Unitfed States Highway 

 No. 17, about 1 mile south of Monck's Corner, Berkeley County, 

 S. C. 



SIGMOMORPHINA WILLIAMSONI (Terquem) 



Plate 38, figures 3, 4 



Polymorphina williamsoni Terquem, Mem. Soc. Geol. France, ser. 3, 



vol. 1, 1878, p. 37. 

 Polymorphina lactea Walker and Jacob var. oblonga Williamson, Recent 



Foram. Great Britain, 1858, p. 71, pi. 6, figs. 149, 149a. — Millett, 



Journ. Roy. Micr. Soc, 1903, p. 262, pi. 5, fig. 5. — Chapman, Journ. 



Linn. Soc. Zool., vol. 30, 1910, p. 413, pi. 55, fig. 12.— Ctjshman,- Bull. 



104, U. S. Nat. Mus., pt. 4, 1923, p. 147, pi. 40, figs. 7, 8. 

 Polymorphina compressa Egger, Abhandl. kon. bay. Akad. Wiss., Miinchen, 



CI. II, vol. 18, 1893, p. 309, pi. 9, figs. 11-13. 

 Polymorphina formosa Egger, Abhandl. kon. bay. Akad. Wiss., Miinchen, 



CI. II, vol. 18, 1893, p. 440, pi. 9, figs. 17-19. 

 Polymorphina mucronata Terquem (not Terquem, 1878), Essai Class. 



Anim. Dunkerque, 1881, p. 130, pi. 17, fig. 3. 

 Polymorphina oblonga, H. B. Brady, Parker, and Jones, Trans. Linn. 



Soc, vol. 27, 1870, p. 222, pi. 39, figs. 7a, &.— Terquem, Essai Class. 



Anim. Dunkerque, 1875, p. 37, pi. 5, fig. 11. — Heron- Allen and 



Earland, Proc Roy. Irish Acad., vol. 31, pt. 84, 1913, p. 100, pi. 8, 



fig. 17. 

 Dimorphina millettii Sidebottom, Journ. Ro}^ Micr. Soc, 1918, p. 145, 



pi. 5, figs. 15, 16. 



Test ovate to oblong, compressed, of nearly equal thickness, sides 

 nearly parallel, rounded at both ends; chambers elongated, embracing, 

 arranged in a contraclockwise, sigmoid series, each succeeding 

 chamber extending down to the base; sutures scarcely depressed, 

 but distinct; wall smooth, thin, nearly transparent; aperture long, 

 radiate, furnished with an entosolenian tube. 



Maximum length 0.92 mm.; breadth 0.42 mm.; thickness 0.20 mm. 



Sigmomorphina williamsoni is a well-marked species and is first 

 recorded by Williamson from Southport, England, under the name 

 "Polymorphina lactea var. oblonga." Brady, Parker, and Jones 

 used the varietal name as the specific name, but much later Terquem 

 changed the name "oblonga" to "williamsoni," as oblonga is pre- 

 occupied by d'Orbigny. 



Polymorphina formosa Egger and P. mucronata Terquem, charac- 

 terized by an oblong test with almost parallel peripheries, resemble 

 the present species and can be included in it, although P. mucronata 

 has a spine at the mitial end. 



Polymorphina compressa Egger (not Philippi, not d'Orbigny) is 

 rather shorter than the typical specimen, but is to be placed in the 

 synonymy of the present species. 



Often the present species apparently shows an alternating chamber 

 on one side on account of an incomplete overlapping of chambers, but 

 the real arrangement of the chambers is always sigmoidal. 



