50 BULLETIN 161, UNITED STATES NATIONAL MUSEUM 



ELPHIDIUM MACELLUM (Fichtel and Moll) var. LIMBATUM (Chapman) 



Plate 11, Figures 9a, b 



Polystomella macella (Fichtel and Moll) var. limbata Chapman, Joum. Quekett 

 Micr. Club, ser. 2, vol. 10, p. 142, pi. 10, figs. 9o, b, 1907. 



Chapman described this variety from off AustraUa. It has the 

 umbilical region depressed, and the periphery subacute, but the 

 sutures are raised. The only specimens we have that can be perhaps 

 referred to this form are from 12 fathoms off Levuka, Fiji, and off 

 Niau. 



ELPHIDIUM ADVENUM (Cushman) 



Plate 12, Figures 1-3 



Polystomella subnodosa H. B. Brady (not Miinster), Rep. Voy. Challenger, 

 Zoology, vol. 9, p. 734, pi. 110, figs, la, b, 1884.— Chapman, Joum. Linn. 

 Soc. Zool., vol. 28, p. 203, 1901.— Millett, Journ. Roy. Micr. Soc, 1904, 

 p. 604.— Bagg, Proc. U. S. Nat. Mus., vol. 34, p. 165, 1908.— Heron-Allen 

 and Earland, Trans. Zool. Soc. London, vol. 20, p. 733, 1915. 



Polystomella advena Cushman, Carnegie Inst. Washington Publ. 311, p. 56, pi. 

 9, figs. 11, 12, 1922; Carnegie Inst. Washington Publ. 342, p. 48, 1924; 

 Carnegie Inst. Washington Publ. 344, p. 80, 1926. 



Elphidium advenum Cushman, U. S. Nat. Mus. Bull. 104, pt. 7, p. 25, pi. 10, 

 figs. 1, 2, 1930; Florida State Geol. Surv. BuU. 4, p. 40, pi. 7, figs. 7o, 6, 

 1930. 



Test equally biconvex, periphery acute, often with a narrow keel, 

 and in the last-formed portion somewhat lobulate in side view, 

 umbilical region usually with a small boss; chambers niunerous, 

 somewhat inflated, especially in the last-formed portion; sutures 

 depressed, the retral processes in the later portion only about one- 

 fourth the width of the chamber, in depressed channels above the 

 sutures the intermediate portions raised; wall smooth, translucent, 

 very finely perforate; aperture a series of rounded pores, at the base 

 of the apertural face of the chamber. Diameter, up to 0.8 mm; 

 thickness, 0.35 mm. 



Table 28. — Elphidium advenum — material examined 



