STUDIES m FORAMmiFERA 



145 



completely developed chamber which occupies the full 

 breadth of the test. Megalospheric specimens are also 

 figured for the same species. 



Neither Neugeboren nor Cushman figured complete 

 specimens. The apertiu-e in the early stages consists 

 of radiating grooves from the mid-point of the apertural 

 region. The ribs between these grooves converge in 

 later growth, meeting centrally and leaving open 3 to 

 6 pores between the strong radial costae, forming a 

 cribrate aperture. A similar aperture was described 

 and figured by Glaessner (1936, p. 117, pi. 2, figs. 9, 14). 

 No internal plates or tubes are visible. 



The characters as now described suggest a close re- 

 lationship of Amphimorphina and Plectqfrondicularia, 

 as stated by Glaessner (1936, p. 120; 1945, p. 138) and 

 Pokorny (1954). Because of their striking morpho- 

 logical similarity, the two genera are here placed in 

 the Plectofrondiculariinae. 



The tjrpe species of Nodomorphina Cushman, 1927, 

 is Nodosaria compressiuscula Neugeboren, 1852. No 

 specimens of this species were available in the U. S. 

 National Museum. However, the generic diagnosis 

 given by Cushman strongly suggests that this genus is 

 synonymous with Amphimorphina Neugeboren. The 

 only difference cited by Cushman is the complete 

 uniseriality of the test (the quadrangular section of 

 the test in the early stage is a common character in 

 Amphimorphina also). But most specimens of Amphi- 

 morphina are megalospheric, and also show an uniserial 

 arrangement of the chambers. The similarity of all 

 the other characters suggests much doubt as to the 

 separate validity of this generic name, and its sup- 

 pression is recommended. 



Family Buliminidae Jones, 1876 



Subfamily Bolivinitinae Cushman, 1927 



Genus Bolivinoides Cushman, 1927 



Plate 33, F cures 14-16 



Bolivinoides Cushman, Contr. Cushman Lab. Foram. Res., 

 vol. 2, p. 89, 1927. 



Type species: Bolimna draco Marsson, 1878, Cre- 

 taceous Weisse Schreibkreide, from the Isle of Riigen, 

 Germany. 



Diagnosis: Test biserial from the early stage, 

 cuneiform, gradually increasing in breadth, with final 

 chamber umbonate. Initial chambers near the pro- 

 loculum more or less arched, and sometimes enveloping. 

 Sutures oblique, slightly curved, at a 45-degree angle 

 with the horizontal, thickened, flat. Wall calcareous, 

 minutely perforate, internally tuberculate, and extern- 

 ally costate and tuberculate, giving a generally strong 

 longitudinal ornamentation. Aperture narrow, gen- 

 erally basal, symmetrical, frequently provided extern- 

 ally with a lamellar lip and internally with a columeUar 

 toothplate, disposed axially between the two series of 

 chambers and extending from the proloculum. 



Discussion: This Cretaceous and Paleocene genus 

 was incompletely described, and was originally placed 

 in the Heterohelicidae. This systematic position was 

 corrected by Glaessner (1945) who placed the genus 

 in the superfamily Buliminidea, family Buliminidae, 

 subfamily Bolivininae, considering Bolivinoides only a 

 subgenus of Bolivina. The same position was accepted 

 by Sigal. 



In the last few years Hiltermann and Koch (1950), 

 Reiss (1954) and Edgell (1954) published statistical 

 researches on the stratigraphical variability of this 

 genus, with particular attention to the variability in 

 shape and ornamentation. Hofker (1952) noted the 

 existence of a "toothplate" and attempted a reconstruc- 

 tion of the internal structure of the test. 



The present work partially confirms Hofker's results, 

 and gives some new structural information. The 

 biseriality of the early stage is confirmed. Hiltermann 

 and Koch (1950, p. 598) suppose that "der scheinbar 

 planispirale Aufbau der Embryonal-kammern findet 

 sich nach unseren Material nur bei einen kleinen TeQ 

 der Individuen und ist auch bei megalospherischen 

 Formen zu beobachten." The simulated appearance 

 of a coiled initial stage can be explained, because in 

 the most extended forms of this genus, as for instance, 

 Bolivinoides draco draco (Marsson), the first two cham- 

 bers formed after the proloculum are almost completely 

 enveloping, in both the micro- and megalospheric 

 forms. Actually, the biseriality is a constant character. 



The aperture was correctly described by Hofker. In 

 the specimens observed, the aperture is proportionally 

 narrower and more reduced than was figured by Hilter- 

 mann and Koch. Furthermore the margin of the 

 aperture is reduced at the surface to a thin lip, which 

 can become lamellar in the better preserved specimens. 

 This lamellar Hp is not continuous, but is generally 

 situated on the side opposite to that of the toothplate. 

 The aperture is surroimded by a narrow depressed area. 



The toothplate is externally visible in many speci- 

 mens. Internally it is modified to form a tubular 

 columella, which is visible in the figured sectioned 

 specimen (fig. 14), and also in others not here figured 

 but prepared with acid by the writer (Cushman Coll. 

 16267, 12108). 



Hiltermann and Koch (1950, p. 597) described the 

 internal structure as follows: "jede Kammer iiberdeckt 

 die darunter liegende mit ihrer aussen etwas herabge- 

 zogenen Kammerbasis ; die Einzelkammern besitzen eine 

 Anzahl zu ihrer Basis rechtwinkhg angeordnete Kam- 

 mervertsatze, die auf die darunter liegende Kammer 

 iibergreifen; diese bilden die Skulptur und treten als 

 Kjioten oder Rippen auf. . . . ; die Suturen werden 

 dadurch entsprechend verdeckt imd sind bei aus- 

 gesprochenen Rippenskulptur sogar unsichtbar. . . . 

 Kammerraum langlich halbmondformig; Anfangsteil 

 verjiingt, manchmal etwas verdreht." 



Hofker (1952, p. 379, figs. 3 and 4) gives an interpre- 

 tation which needs correction. His figure 3b indicates 

 thin sutures crossed by perpendicular processes. In 

 figure 3c ("in optischen Schnitt") septal marginal folds 



