148 



UNITED STATES NATIONAL MUSEUM BULLETIN 215 



pi. 7, figs. 3-7) recently refigured the conspecific 

 "holotype" of Eouvigerina excavata Cushman, and the 

 holotype and two hypotypes of the congeneric T. 

 costifera (Cushman), hence these are not here refigvired. 



Subfamily Eouvigerininae Cushman, 1927 

 Genus Eouvigerina Cushman, 1926 



Plate 34, Figures 1-7 



Eouvigerina Cushman, Contr. Cushman Lab. Foram. Res., vol. 

 2, p. 4, 1926. 



Type species: Eouvigerina americana Cushman, 

 1926, Upper Cretaceous Taylor marl, from pit of 

 Dallas Brick Company, K mile west of Mesquite, 

 Dallas County, Texas. 



Diagnosis: Test smaU, biserial throughout, com- 

 monly twisted and thus may simulate an appearance 

 of triseriality. The chambers immediately following 

 the proloculum are reniform and arranged longi- 

 tudinally on opposite sides of the proloculum, giving a 

 round outline and a false coiled appearance to the 

 neanic stage. In the adult the commonly loosely 

 arranged chambers are more inflated, assuming a 

 pyriform or, if carinate, subtriangular shape. When 

 the chambers are overlapping and carinate, the test 

 becomes subrectangular in cross section. The final 

 chamber is nearly central in position. Wall calcareous, 

 surface finely perforate and frequently more or less 

 spinose. Strong carinae may be present in the mature 

 stage, following the length and the curvature of the 

 chambers and consequently becoming horizontal, arched 

 and finally sub vertical or vertical. 



Aperture terminal, with a more or less well developed 

 neck and lip. One or two thin transverse ridges may 

 appear on the surface of the neck. Internally the 

 aperture has a thin columeUar process (fig. 2) which is 

 also visible in the young stage. 



Discussion: Loeblich (1951, p. 109), after restudying 

 the types, substantiated the description of Glaessner 

 (1945, p. 138), correcting the original generic diagnosis 

 of Cushman by recognizing the absence of a coiled 

 early stage, and the complete biseriality of this genus, 

 tending to a uniserial development. 



The use of high magnification and numerous partially 

 acid-treated specimens in the present study revealed 

 the presence of an internal columellar process, extending 

 from the very young chambers of the test up to the 

 aperture. Because of the small size of the test, the 

 tubular nature of this process is visible only in the last 

 chamber and the shape of this very thin "toothplate" 

 and the position of its departure from the aperture 

 could not be determined. 



Another investigation of some interest concerned the 

 relationship of the external shape in the different 

 species of Eouvigerina to the (1) shape and position of 

 each chamber, and (2) presence, position and develop- 

 ment of the carinae, which are more or less well devel- 

 oped in nearly all the species. 



There is a great variability in the form of the test. 



and a separation into different species often cannot 

 easily be made. If the Paleocene species Eouvigerina 

 excavata Cushman, which is conspecific with Tappanina 

 selmensis (Cushman), is excluded, it can be said of 

 Eouvigerina that the test is frequently twisted, a fact 

 that lead Cushman and others to believe it triserial; 

 and the change in shape in the mature stage is gradual, 

 and is related to the development and the overlap of 

 the pyriform chambers, and the strength of the carinae. 

 An example without carinae is E. fragilis (Terquem), 

 which has uvigeriniform later chambers. When the 

 carinae are strongly developed, the pyriform chambers 

 become subtriangular in top view, which may lead to 

 different test shapes, according to the more or less 

 close arrangement of the chambers. Chambers closely 

 arranged and carinate, but not large or much arched, 

 have a Tappanina-like appearance, subrectangular in 

 cross section and depressed on the broader faces, as in 

 E. serrata (Chapman) and E. americana Cushman 

 (part). When the chambers are carinate, loosely 

 arranged, twisted (as in USNM P4887), and tend to 

 become almost uniserial, a false triserial appearance is 

 given, when viewed from above, as in typical E. ameri- 

 cana Cushman. 



Eouvigerina plummerae is a very distinctive form. 

 As the present research is an analytical restudy of the 

 genera as based on their type species, a discussion of 

 each species is out of place. Nevertheless as some 

 "transitional" specimens are in the U. S. National 

 Museum, it is perhaps of some interest for further 

 discussion to show such specimens, and two aberrant 

 specimens of E. americana for comparison. If this 

 species belongs to another genus — as there is evidence 

 to believe — it must in any case be related to Eouvigerina. 

 The chambers are elongate and strongly arched, losing 

 the lateral portion of the carinae (as is also true in 

 aberrant E. americana, figs 3, 5), become closely ap- 

 pressed and overlapping, with fusion of the arched 

 cariaae on the sides of the broader faces from the early 

 stage, giving four sharp vertical Bolivinita-like lamellae, 

 although the species is clearly distinguishable from 

 Bolivinita by the different aperture. An appearance of 

 similarity seems to exist between E. plummerae and 

 Bolivinitella. Nevertheless the latter genus has a 

 quite different aperture and lacks an apertural or 

 columellar proccess. 



The results of the studies of this genus by Glaessner 

 (1945), Loeblich (1951) and the present study aU show 

 clearly that neither the morphological nor structural 

 characters of Eouvigerina show any relationship to the 

 true Heterohelicidae. 



Genus Siphogenerinoides Cushman, 1927 



Plate 34, Figures 8-10 



Siphogenerinoides Cushman, Contr. Cushman Lab. Foram. Res., 



vol. 3, p. 63, 1927. 



Type species: Siphogenerina plummeri Cushman, 



1927, Upper Cretaceous, Maestrichtian, from bank of 



Walker Creek, 6 miles N.15° E. of Cameron, about 1 



