20 



UNITED STATES NATIONAL MUSEUM BULLETIN 215 



Globorotaliidae Cushman, 1927 



Praeglobotruncana Bermudez 



Rotalipora Brotzen 



Globorotalia Cushman 



Truncorotaloides Bronnimann and Bermudez 

 Globotruncanidae Brotzen, 1942 



Abathomphalus Bolli, Loeblich, and Tappan 



Rugoglobigerina Bronnimann 



Globotruneana Cushman 

 Orbulinidae Schultze, 1854 



Globigerininae Carpenter, 1862 



Globigerina d'Orbigny 



Globoquadrina Finlay 



Hastigerinella Cushman 



Globigerinoides Cushman 



Sphaeroidinella Cushman 



PuUeniatina Cushman 

 Orbulininae Schultze, 1854 



Globigerapsis Bolli, Loeblich, and Tappan 



Porticulasphaera BoUi, Loeblich, and Tappan 



Candeina d'Orbigny 



Orbulina d'Orbigny 

 Catapsydracinae Bolli, Loeblich, and Tappan, new 

 subfamily 



Catapsydrax Bolli, Loeblich, and Tappan 



Globigerinita Bronnimann 



Globigerinoita Bronnimann 



Globigerinatheka Bronnimann 



Globigerinatella Cushman and Stainforth 



The families of planktonic genera have been sepa- 

 rated by earlier classifications variously on the external 

 form of the test, t3rpe of coiling, or a combination of 

 characters of varied importance, including sm-face 

 ornamentation; and the families have been considered 

 to properly include genera of differing wall structure, 

 apertural characters, etc. These bases for separation 

 have obviously not proved entirely successful, as cer- 

 tain genera have been placed in one family after 

 another by successive workers, while the family and 

 subfamily limits have varied widely in the different 

 classifications. 



Furthermore, little attention has been paid in the 

 past to the priority status of family and subfamily 

 names. Under the Kules of Nomenclature the family 

 and subfamily names are treated as equal for purposes 

 of priority. For this reason, the oldest name used for 

 either a family or subfamily, based on a genus placed 

 within the family, must be used as the valid family 

 name, and if the family is divided into subfamilies, the 

 subfamily containing the type genus of the family must 

 also bear the name based on that genus. 



Bases for Classification 



Morphologic evidence: In the present classifica- 

 tion the morphology of the test is used as the primary 

 basis. The families under consideration here are all 

 alike in possessing a calcareous, perforate-radial wall, 

 hence all genera with perforate granular walls are 

 excluded. Similarly, these radial-walled genera cannot 

 be placed within families characterized by granular 

 walls. 



The apertiu-al position is considered second in im- 

 portance only to the wall composition and structure. 

 It is always a constant character in the adult, and one 



of the few characters which does not change with 

 environmental changes. It may change in size and 

 position in the ontogeny of the individual, but these 

 changes are always the same in each individual of the 

 species. Thus, they are also extremely valuable in 

 showing relationships, for the aperture in the young 

 stage is like that of the ancestral form, and there may 

 be intermediate ancestral characters also shown in the 

 gradual development of the adult characters. 



The type of chamber development, primarily the 

 type of coiling, is third in systematic importance within 

 these groups. Thus, the Orbulinidae, Globorotaliidae, 

 and Globotruncanidae, all have a basic trochospiral 

 coiling. Specialized genera may develop modifications, 

 but trochospiral coiling is nonetheless present in their 

 early ontogenetic stages. Similarly the Hantkeninidae 

 have a basically planispiral development. 



The characteristic modifications of apertures, changes 

 from simple to multiple apertures, from open to covered, 

 or from an interiomarginal to an areal position, are 

 fourth in importance. 



Modifications of the chambers and the resultant test 

 form are fifth in importance. In the planktonic groups 

 this is generally expressed in one of two ways, a tend- 

 ency to develop a radially expanding test or a tendency 

 to develop a globular test. 



Last are the more detailed characters of size and 

 relative proportions of test, chambers, and apertiu-es 

 and ornamentation. 



Evidence from ontogeny: The well known biologic 

 theory that "Ontogeny recapitulates phylogeny," has 

 also been a basis used in the present classification. 



Dissections of many of the species have shown that 

 they pass through early stages that resemble other 

 genera. For example, specimens of the genus Globig- 

 erinoita pass through an early 6lobigerimi-\ike stage, 

 then a Globigerinoides stage, and finally develop the 

 adult characters peculiar to their own genus. This 

 ontogenetic development shows the family relationship 

 between these genera, although the adult characters of 

 Globigerinoita, in particular the development of the 

 secondary bullae over the apertural openings, are con- 

 sidered of sufficient taxonomic value to place this genus 

 in a separate subfamily. Similarly the early trocho- 

 spiral development and GlobigerinaAike umbilical aper- 

 ture of the young stage of Hastigerinella suggest that it 

 should be placed with Globigerina rather than with 

 Hastigerinoides, which it resembles only in the pelagic 

 adaptation of developing radial-elongate chambers. 

 This latter character is obviously due to convergence, 

 as a similar flattening or spreading in a plane is de- 

 veloped merely as an aid to flotation in many other 

 groups of pelagic animals. 



Stratigraphic distribution: In order to devise a 

 logical classification, the geologic occurrence should 

 also be considered. The ancestral forms should of 

 course be those foimd earliest in the geologic record, 

 although in some proposed classifications certain 

 "ancestral types" were found only in relatively young 

 strata. 



