18 BULLETIN 104, UNITED STATES NATIONAL MUSEUM 



Jurassic to Recent. 



The retral processes characteristic of this genus are variously 

 developed. In some primitive species they are hardly developed but 

 in others they become very highly developed together with the canal 

 system of the interior of the wall. In the larger tropical species of 

 the Indo-Pacific the umbilical bosses become very highly developed 

 with large pores, and the chambers are very numerous. There are a 

 great many species as might be expected in such a highly developed 

 genus, and their geographic ranges are well defined. 



ELPHIDIUM ALVAREZIANUM (d'Orbigny) 



Plate 7, figures 1-3 



Polystomella alvareziana D'OaBiQNY, Voy. Amer. M6rid., vol. 5, pt. 5, 1839, 

 "Foraminifdres," p. 31, pi. 3, figs. 11, 12. 



Test much compressed, periphery subacute, not carinate, margin 

 entire, even, sides nearly parallel in peripheral view, umbilical re- 

 gions not umbonate; chambers not inflated, 10 to 12 or more in num- 

 ber in the last-formed coil; sutures not depressed, marked by the 

 retral processes which are short and broad, 7 to 8 in number; aper- 

 ture composed of several rounded openings at the base of the apertural 

 face. 



Diameter, 0.60 mm.; thickness, 0.20 mm. 



D'Orbigny's types were from "Patagonia, not far from the Rio 

 Negro and in sands from the Falklands." Specimens comparable to 

 this species as figured and described by d'Orbigny occur in material 

 collected by Dr. Waldo Schmitt from the coast of South America and 

 from the the Falklands. Specimens of this same general form from 

 as far north as the West Indies may also be placed in this species. 



The last chamber as mentioned by d'Orbigny and as is usual in 

 many species of Elphidium is somewhat inflated, due possibly to 

 reproductive conditions. 



ELPHIDIUM INCEKTUM (Williamson) 



Plate 7, figures 4-9 



Polystomella umbilicatula, var. incerta Williamson, Rec. Foram. Gt. Britain, 



1858, p. 44, pi. 3, figs. 82, 82a. 

 Polystomella striato-pundata, var. incerta Kiaer, Rept. Norwegian Fish. Mar. 



Invest., vol. 1, No. 7, 1900, p. 51. — Cushman, Rep't Canadian Arctic 



Exped., pt. M, 1913, p. 10. 

 Polystomella decipiens Heron-Allen and Earland (not Costa), Trans. 



Linn. Soc. London, ser. 2, vol. 11, 1916, p. 282, pi. 43, figs. 20-22. 



Test of small size for the genus, compressed, periphery broadly 

 rounded, margin entire or with the last two or three chambers lobu- 

 lated, umbilical regions slightly depressed, often with a slight knob or 

 irregularly arranged slits at the base of the sutures; chambers few, 

 usually less than ten in the last-formed whorl, slightly if at all inflated, 

 distinct; sutures distinct, mainly marked by the openings which are in 



