STUDIES IN FORAMmiFERA 



141 



opening internally and leaving a broad opening between 

 the chambers and the central area. Guhlerina thus 

 represents one of the most distinctive genera in the 

 family Heterohelicidae. 



Variable characters are (1) the width of the central 

 cavity, where an incomplete central chamber occasion- 

 ally appears, and the broad opening from the chambers 

 into the wide central cavity; (2) the development of the 

 granulated ornamentation; (3) the presence, size, 

 depression, and evidence of bubbles in the central area ; 

 and (4) the external lateral inflation of the chambers and 

 consequently the sharpness of the transverse section. 

 A comparison of G. ornatissima and G. decoratissima 

 emphasizes the constant and the variable characters of 

 this very distinctive genus. 



Some other synonyms of species of Gublerina have 

 been suggested by Bronnimann and Brown (1954). 

 Gublerina hedbergi Bronnimann and Brown was stated 

 to be a syno lym of G. acuta robusta de EQasz, and 

 Gublerina afl. G. cuvillieri Kikoine described by de 

 Klasz (1953, p. 248, footnote 1, pi. 8, figs. 2a, b) is the 

 same as G. glaessneri Bronnimann and Brown. 



The investigation of the structure of the central area 

 of the test, and the statement that central internal 

 chambers do not occur in Gublerina but are so simulated 

 by more or less irregular bubbles and external orna- 

 mentation, suggest the advisability of reexamining 

 many of the specimens interpreted as Gublerina and 

 figm'ed with one or more completely developed central 

 chambers. Such a character (central internal cham- 

 bers), when actually occurring in flabelliform specimens, 

 represents Planoglobulina, not Gublerina. On the other 

 hand, specimens where the reniform chambers are ar- 

 ranged in two diverging series, separated by a non- 

 septate central area but without proliferation at the 

 top of the test, are representatives of aberrant forms 

 (although stiU of Gublerina) which tend toward the 

 extreme limits of variability of the genus Heterohelix 

 (H. tessera, H. pulchra, H. lata). 



A paratype of Gublerina hedbergi {=G. acuta robusta 

 de E[lasz) examined for this study shows that following 

 an early coiled stage there are eight chambers with a 

 typical guembelinoid development (chambers inflated 

 and sutures deep and narrow) . The four mature cham- 

 bers which follow become reniform and depressed in the 

 central area, simulating, because of their irregularity, 

 the presence of one or more internal chambers. Actu- 

 ally an observation of both sides of the test by trans- 

 mitted light shows no traces of sutures in this area. 

 The fragmentary final two chambers in this paratype 

 show only a bicamerate end stage, not multicamerate 

 as in Gublerina, even though the wide central area, 

 typical of this genus, is present. A comparison with 

 forms like Heterohelix pseudotessera {—H. pulchra) and 

 H. lata can be made through the illustrations given here. 



Thus, the genus Gublerina can be interpreted as very 

 distinctive, with its morphological and genetical posi- 

 tion between Heterohelix and Planoglobulina. 



Genus Planoglobulina Cushman, 1927 

 Plate 32, Figures 10-13 



Planoglobulina Cushman, Contr. Cushman Lab. Foram. Res., 



vol. 2, p. 77, 1927. 

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



4, p. 2, 1928. 



Type species: Guembelinaacervulinoides Egger, 1900. 

 Upper Cretaceous Senonian of Bavarian Alps. Numer- 

 ous localities and horizons were listed, none designated 

 as type. The synonymous Ventilabrella was also defined 

 without citation of a type specimen, horizon, or locality 

 in either the generic definition or the description of the 

 type species, V. eggeri Cushman. 



Diagnosis : Test biserial in the young stage, later with 

 a more or less abundant proliferation of globular cham- 

 bers, which spread out in the plane of biseriality, giving 

 a flabelliform shape to the test. Wall calcareous, finely 

 perforate, and commonly striate on the surface. Aper- 

 ture multiple on the final series of chambers, which 

 may be numerous. 



Discussion: This genus can easily be distinguished 

 from Gublerina by the absence of costate sutures and 

 the globular and completely developed chambers in the 

 area of proliferation. 



A comparison of the figures of complete and sectioned 

 specimens of Gublerina and Planoglobulina emphasizes 

 these differences better than does a discussion. Speci- 

 mens from the Cushman Collection (31839 and 31861) 

 also demonstrate these elements well. 



According to the present redescription and emended 

 diagnosis of the genus Gublerina, Ventilabrella decora- 

 tissima de Klasz is a typical Gublerina. The figure 

 given by de Klasz (1953) seems to represent a real 

 Ventilabrella {= Planoglobulina) . However, examina- 

 tion of a paratype in the de Klasz collection in the 

 U. S. National Museum, shows somewhat different 

 ornamentation and character of chambers, and an 

 internal structure typical of a Gublerina. 



A young specimen of Planoglobulina eggeri (Cushman) 

 var. glabrata (Cushman) shows the derivation of 

 Planoglobulina from a globulosa-\ike Heterohelix. 



The generic name Ventilabrella has commonly been 

 used for this group of species, but is a synonym of 

 Planoglobulina. Both genera were described by Cush- 

 man, who stated that Planoglobulina arose from a 

 Pseudotextularia stage and Ventilabrella from a Guem- 

 belina stage. Planoglobulina was defined in 1927, and 

 the type designated as Guembelina acervulinoides Egger. 

 Cushman (1927b) stated that it had a planospiral early 

 stage, followed by a biserial stage and finally a pro- 

 liferation of chambers in a single plane. The following 

 year Cushman (1928) defined Ventilabrella, citing as 

 type the new species V. eggeri, and stating that it 

 developed from a biserial stage, with later proliferation 

 of chambers in a single plane. In his description of the 

 type species he also stated that the microspheric form 

 probably also was planispiral in the early stage. 



