STUDIES EST FORAMINIFERA 



137 



minuta Natland, also living, is not a Guembelitria but 

 because of the clearly trochoid coiling probably is a 

 Globigerinid. 



Genus Guembelitriella Tappan, 1940 



Plate 31, Figures 3, 4 



Guembelitriella Tappan, Journ. Paleontol., vol. 14, p. 115, 1940. 



Type species: Guembelitriella graysonensis Tappan, 

 1940, Cretaceous Grayson formation (Cenomanian) , 

 from Grayson Bluff, 3K miles northeast of Roanoke, 

 Denton County, Texas. 



Original diagnosis: "Test free, small, triserial in 

 the early stage, similar to Guembelitria, later becoming 

 multiserial on the top; chambers globular, increasing 

 rapidly in size; sutures distinct, depressed; waU cal- 

 careous, finely perforate; aperture at base of the final 

 chamber." 



Discussion: No addition to the diagnosis given by 

 Tappan is necessary. This genus is a further develop- 

 ment from Guembelitria, becoming multiserial in the 

 adult, a development parallel to that shown by Plano- 

 globulina from the Heterohelix group. Consequently, 

 the separation of this genus by Tappan has the same 

 validity as the separation of Planoglobulina from 

 Heterohelix. It is of some interest that Tappan also 

 noted the presence of accessory apertures in this genus. 

 A discussion of this general character is given in the 

 discussion of Pseudoguembelina Bronnimann and Brown. 



Subfamily Heterohelicinae Cushman, 1927 



Genus Heterohelix Ehrenberg, 1841 



Plate 31, Figures 5-20 



Heterohelix Ehrenberg, Abhandl. Akad. Wiss. Berlin, p. 429, 



1841. 

 Guembelina Egger, Abhandl. Akad. Wiss. Munchen, Classe ii, 



vol. 21, p. 31, 1889. 



Type species: Spiroplecta americaria Ehrenberg, 

 1844, Cretaceous, from Missouri and Mississippi, 

 North America (not since recognized). 



Diagnosis: Test calcareous, biserial or planispiral in 

 the early stage, always biserial in the adult stage. 

 Chambers generally inflated, globvdar to reniform. 

 Wall calcareous, perforate, surface smooth or striate. 

 Aperture basal, relatively large, with simple margin. 



Discussion: Heterohelix and Guembelina were con- 

 sidered by Cushman (1927a, p. 59) as representative 

 of two different subfamilies of the Heterohehcidae, i. e., 

 Heterohelicinae and Guembelininae. The distinctive 

 character was considered to be the presence in the 

 Heterohelicinae of a coiled early stage, "forming a 

 considerable portion of the test." For Guembelina, the 

 test was indicated as "in the early stage of the micro- 

 spheric form planispiral, often skipped in the megalo- 

 spheric form." 



Galloway (1933,p. 343) adopted the same systematic 

 subdivision, stating that Guembelina "differs from 

 Heterohelix only in the absence of the spiral, early 



Glaessner (1945) does not cite the genus 

 Heterohelix. 



Sigal (1952) even placed Heterohelix and Guembelina 

 in two different superfamilies. Heterohelix he placed 

 in the superfamily Buliminidea, family Heterohehcidae, 

 subfamily Heterohelicinae, with Bolivinopsis and Nodo- 

 planulis — and included in the family the two subfami- 

 Ues Bolivinitinae and Plectofrondiculariinae of Cush- 

 man, emended. Guembelina was placed in the super- 

 family Rotaliidea, family Guembelinidae, between the 

 famihes Globorotaliidae and Elphidiidae. 



Thus, the previous separation of the two genera was 

 based substantially on the presence of a well-developed, 

 coiled early stage in Heterohelix, and rare or no coUing 

 in Guembelina. 



Loeblich (1951) published a discussion of the phylo- 

 genetic relationships of the Heterohehcidae of Cushman, 

 and illustrated specimens with a coiled early stage not 

 only in Heterohelix, but also in Guembelina {G. globulosa 

 (Ehrenberg)), and Ventilabrella {= Planoglobulina) {V. 

 carseyi Plmnmer). Concerning G. globulosa he noted 

 (1951, p. 108) "an extremely tiny initial coil of about 

 five chambers, followed by 11 to 12 biserially arranged 

 chambers," and for Heterohelix (1951, p. 107) "five to 

 six chambers of the coil," with "sLx to eleven biseriaUy 

 arranged chambers." For the present study, more than 

 3,000 specimens of Heterohelix and Guembelina were 

 examined under high magnification (x 216) and, when 

 necessary, also by immersion in anise oil. No critical 

 examination was made of the validity of the numerous 

 species of both Heterohelix and Guembelina, as this was 

 aside from the main purpose of this study; therefore, 

 in the following lists there may be some specific names 

 which may later be proven to be synonymous. The 

 total number of specimens examined, and the number 

 and percentage of specimens with an initial coil are 

 given below for the various species: 









Number 



Percent 



Name 





Specimens 



coiled 



coiled 



G. globulosa 





447 



113 



25.3 



G. globocarinata 





1,067 



175 



16. 



G. carinata 





4 



2 



50. 



G. planata 





5 



4 



80. 



G. striata 





130 



6 



3.8 



G. glabrans 





6 



2 



30. 



G. reussi 





2,000 



12 



0.5 



G. pseudotessera (=G. 



pulchra) 



127 



5 



3.9 



G. cubensia 





45 







G. ultimatumida 





15 







G. venezuelana 





42 







G. trinitatensis 





1 







G. wilcoxensis 





2 







It is necessary to remark, in considering these statistical 

 data, that only the specimens with absolutely clear 

 coiling are indicated in the percentage of the spiral 

 forms. Many specimens have an asymmetrical en- 

 largement of the test, with a slightly curved initial 

 stage and sometimes an additional asymmetrical 

 chamber near the proloculus. Nevertheless they were 

 not added to the "spu-aling" list. Many specimens 

 from the early upper Cretaceous (ex. G. moremani 

 Cushman) have a poorly preserved test, commonly 



