8 BULLETIN 161, UNITED STATES NATIONAL MUSEUM 



Atlantic realm are as Tertiary fossils: the Oligocene of Mississippi 

 and the Eocene of Georgia. 



As compared with P. corrugata Williamson from off the British 

 Isles, the test of P. advena is lower and is more nearly dome shaped 

 than peaked, and the septa are much more lobed and complex. In 

 addition, the dorsal sutures are nearly indistinguishable in P. advena, 

 whereas in P. corrugata they are distinct and sometimes even slightly 

 limb ate. 



Comparison with unfigured types of P. corrugata var. jormosa 

 from 118 meters, Burdwood Bank in the Falkland Islands, sent by 

 Mr. Earland (Cushman Coll. 14605), leads me to include this form 

 in the synonymy of P. advena. 



PATELLINA ADVENA ALTIFORMIS Cushman 



Plate 1, Figure 1 



Patellina advena Cushman var. altiformis Cushman, 1933, Contr. Cushman 

 Lab. Foram. Res., vol. 9, p. 87, pi. 9, fig. 8.- — Cushman, Todd, and Post, 

 1954, U.S. Geol. Surv. Prof. Paper 260-H, p. 357, pi. 89, fig. 1. 



This high-spired form of Patellina advena seems better regarded 

 as a subspecies than a variety. It is less rare than the typical form 

 and is found in some of the same samples, all but one in relatively 

 shallow water. 



The circumstance of a subspecies occurring in the same sample 

 with the typical form of a species leads one to question how this can 

 be when a subspecies is thought of as a geographically defined (or 

 possibly ecologically defined) subdivision of a species. Because of 

 the probably very minute geographic area occupied by an individual 

 foraminifer, or even by whole populations of Foraminifera, one 

 subspecies may live in what would appear to be rather close geographic 

 proximity to another subspecies yet still be within a geographically 

 defined area. The movement of empty tests of Foraminfera over the 

 sea floor by currents or activity of other benthonic organisms in- 

 creases or entirely changes the apparent geographic distribution of 

 a species or subspecies and serves to obscure the exact geographic 

 area in which any such group actually lived. 



Because of these considerations, it is difficult, if not impossible, 

 to determine accurately whether slight morphologic differences within 

 species correspond to, or are independent of, geographic or ecologic 

 restriction of the living animals. Thus, determination of subspecific 

 relationships in instances such as this are subjective matters. And 

 it is, moreover, not to be unexpected that two or more subspecies 

 would be found in a single sample. 



