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UNITED STATES NATIONAL MUSEUM BULLETIN 215 



as a globigerine form in the family Globotruiicanidae, 

 with a small umbilicus and apertural flaps but no cover 

 plate and no peripheral keel. It was considered to be 

 ancestral to Ticinella [= Rotalipora], although lacking 

 secondary apertures. The type species, Olobigerina 

 seminolensis Harlton, is a Cretaceous species, repre- 

 sented only by the holotype, which was found as con- 

 tamination or a possible outher in the Pennsylvanian 

 from the Ardmore basin of Oklahoma. As the type 

 lacks the most important character of the Globotrun- 

 canidae (the tegilla) it cannot be placed in this family, 

 and the absence of secondary apertures shows that it 

 is not a Ticinella. This type species was an unfortunate 

 selection, as the central portion of the holotype is com- 

 pletely obscured by matrix. As its true stratigraphic 

 position is unknown it cannot be conclusively checked 

 on other material. This poorly preserved specimen 

 (here refigured) could easily be fit into a number of 

 the various species of "Globigerina," Praeglobotruncana, 

 etc., described from the Lower and Upper Cretaceous 

 within a relatively short distance from the Pennsyl- 

 vanian outcrop. Bronnimann and Brown state that 

 the type species, 6. seminolensis, is "rather rough- 

 walled, coarsely granular", with "markedly elongated" 

 chambers, and an interiomarginal aperture, bordered 

 by a short apertural flap, opening into the umbilicus. 

 The holotype of the species is smooth-walled, and has 

 a finely perforate test, and the aperture and umbilicus 

 are both completely obscured by extraneous material. 

 Bronnimann and Brown figured a specimen from Cuba, 

 which they referred to 6. seminolensis, but they did 

 not give any exact stratigraphic data for the Cuban 

 specimen either. The figures of this form also show 

 a filled umbilicus, with no indication of the umbilical 

 and apertural characters they mentioned. Further- 

 more, the chambers of both specimens that have been 

 figured are nearly spherical, and show no indication of 

 the elongation mentioned by Bronnimann and Brown. 

 The only character they indicated which could separate 

 this species from Praeglobotruncana, is the absence of a 

 keel, and this is not considered here to be of generic 

 significance. There are many gi-adations from rounded 

 to shghtly compressed to keeled species in most coiled 

 genera of calcareous Foraminifera. Hence, Hedbergina 

 is tentatively considered to be a synonjrm of Praeglobo- 

 truncana, although, because the position of the aperture 

 cannot be definitely determined on the basis of the 

 material available, it might possibly be a species of 

 Globigerina. 



Praeglobotruncana is regarded as one of the more 

 primitive planktonic genera, and possibly gave rise not 

 only to other genera of the Globorotaliidae but also to 

 the Globotruncanidae and Orbulinidae, and possibly 

 even to the Hantkeninidae. Various early species 

 show tendencies in these various directions. Perhaps 

 the closest relationship is to Globoroialia, which differs 

 in having a more extraumbilical aperture, in being more 

 prominently keeled, and in having ovate to angular 

 chambers. Praeglobotruncana has a resemblance to 



Globigerina d'Orbigny in having spherical or ovate 

 chambers and a more umbilically directed aperture, but 

 differs in the somewhat extraumbilical extension of the 

 apertiire and the faint keel which may be developed in 

 the early stages of some species. The broad apertural 

 lips are also not characteristic of Globigerina. Both of 

 these genera could thus have arisen from Praeglobo- 

 truncana by slight modifications in apertural position 

 and chamber shape. 



Fusion of the apertural lips at their lunbilical margins 

 could leave sutural openings and give rise to the 

 Rotalipora group. A continued increase in the de- 

 velopment of the apertural flaps until they completely 

 covered the mnbUicus and attached at their opposite 

 margin, coupled with a gradual restriction in the 

 position of the aperture from extraumbilical-umbUical 

 to only umbilical, would give rise to Bugoglobigerina 

 and Globotruncana. 



Other species, such as P. subcretacea (Tappan) 

 [=Hastigerinella subcretacea Tappan], show a tendency 

 to develop radially elongate chambers, and may show 

 a relationship to the Hantkeninidae. Schackoina does 

 show a trochospiral coiling, differing only in the 

 restriction of the aperture to a completely extraumbili- 

 cal position and in the development of tubulospines. 



Praeglobotruncana is restricted to the Cretaceous, 

 these globular chambered forms not being found in the 

 same strata as true Globorotalia. Many Cretaceous 

 species originally placed in various other planktonic 

 genera also belong to Praeglobotruncana (i. e., some 

 "Globigerina," "Hastigerinella," "Globorotalia," "Globo- 

 truncana," etc.), as they possess these apertural and 

 test characters in common, but do not have the spe- 

 ciahzed features of the genera to which they had pre- 

 viously been referred. 



Types and occubrence: Holotype of Globorotalia 

 delrioensis Plmnmer (type species of Praeglobotruncana) 

 in the Paleontological Research Institute, Ithaca, New 

 York, from the Cenomanian, Del Rio clay, on right 

 bank of Shoal Creek in a steep slope just south of the 

 Thirty-fourth Street bridge in Austin, Travis Coimty, 

 Texas. Figured topotype (USNM P4481) from the 

 same locality, collected by H. T. and A. R. Loeblich, 

 Jr., July 1940. 



Figured topotype of Globotruncana stephani Gandolfi 

 (USNM P4848), the type species of Rotundina Sub- 

 botina, and unfigured topotype (USNM P4832) from 

 the Cenomanian, Breggia number 56, Canton Ticino, 

 Switzerland. Received from Professor M. Reichel. 



Figured hypotype of Praeglobotruncana planispira 

 (Tappan) (USNM P4875), from the Albian Gault clay, 

 brick pit of the London Brick Co., Arlesey, England. 

 Collected by H. T. and A. R. Loeblich, Jr., 1953. 



Figured holotype of Globigerina seminolensis Harlton 

 (USNM 71380), a Cretaceous specimen erroneously 

 reported to be from the Pennsylvanian (upper Glenn 

 formation) from the SWK, SE^, NW}^ sec. 20, T. 5S., R. 

 IE., Carter County, Oklahoma. 



Range: Aptian to Maestrichtian. 



