FORAMINIFEKA OF THE ATLANTIC OCEAN". 145 



FRONDICULARIA [?J TENERA (Bomemann). 



Plate 21, fig. 5. 



Under this name Heron- Allen and Earland record and figure '* a 

 single specimen from off the west coast of Scotland. There seems 

 to be some doubt as to the exact origin of this specimen and whether 

 it might have been a fossil or not. 



Subfamily 3. Polymorphininae. 



Test polythalamous ; chambers usually arranged in an irregular 

 spiral, in later growth sometimes approaching a biserial arrange- 

 ment or sometimes uniserial; surface smooth or ornamented by 

 spines or costae; aperture radiate. 



This subfamily includes the genus Polymorphina and its closely 

 allied form Diniorplnna. 



Genus POLYMORPHINA D'Orbigny, 1826. 



Poli/morphina D'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 265.— H. B. Brady, 

 Pakxer, and Jones, Trans. Linn. Soc. London, vol. 27, 1870, p. 197, et 

 seq. — H. B. Br.vdy, Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 

 557.— Chapman, The Foraminifera, 1902, p. 199.— Cushman, Bull. 71, 

 U. S. Nat. Mus., pt. 3, 1913, p. 83. 



Description. — Test more or less rounded, usually not equilateral; 

 chambers few, obliquely placed in a more or less spiral arrange- 

 ment; aperture terminal, radiate; wall calcareous, perforate, either 

 smooth or variously ornamented with spines, costae, or tubercles. 



D'Orbigny divided this genus into several subgenera, none of 

 which are at the present time recognized. The literature of this 

 particular genus is more complicated than that of most of the 

 genera, due largely to the fact that so many of the species have 

 a smooth wall without ornamentation and specific characters have 

 to be based almost entirely on the outline and arrangement of the 

 chambers of the test. Allowing for the variation thought to occur 

 in this and other groups of earlier authors, and the lack of close 

 application of names in later work, the number of forms placed 

 under almost any of the smooth species is very great. 



With the limited material at my disposal it is impossible to work 

 out many of these complex cases. I have therefore thought it best 

 simply to give the references under th^ various names to the Atlantic 

 records for the various species, and wait for the future to work out 

 their real relations. That the species of Polymorphina are prob- 

 abl}' as well characterized in their distribution as are other species of 

 other genera radiy be shown by such well characterized species as 

 Polymorphina myristiformis Williamson. This species, which has 

 a peculiar ornamentation, occurs in considerable numbers in a very 

 limited distribution about the British Isles and Western Europe, 



'* Trans. Linn. Soc. London, ser..2, vol. 2, IDIG, p. I'GO, pi. 42, figs. 8-10. 



