STUDIES EST FORAMINIFERA 



117 



Globorotaloides Bolli, new genus 



Type species: Globorotaloides variabilis Bolli, new 

 genus, new species. 



Test free, trochospiral, chambers ovate to spherical, 

 sutures depressed, surface smooth or pitted; primary 

 aperture in the early stage interiomarginal, umbihcal- 

 extraumbilical, later becoming umbilical. Ultimate 

 chamber often smaller than penultimate, may cover part 

 or entire imibihcus and become almost indistinguishable 

 from a biilla. This ultimate chamber normally has a 

 single apertiu-e though multiple ones may occur. 



Remarks: Globorotaloides, new genus, shows in stages 

 the characteristic feature of three planktonic genera. 

 The first stage is that of a Globorotalia with a distinct 

 interiomarginal, umbUical-extraumbilical primary aper- 

 ture, followed by a Globigerina-\ike stage, where the 

 apertiu-e becomes umbilical. The presence of a bulla- 

 like final chamber covering a part or the whole umbUicus 

 indicates the final Catapsydrax-like stage. 



Specimens featuring the early Globorotalia stage only 

 (pi. 27, figs. 15b, 17b) or the following Globigerina-like 

 stage (pi. 27, fig. 19b) were found commonly in the 

 samples studied. The close relationship of these stages 

 with the fully developed Globorotaloides becomes evident 

 when studying a large number of specimens. The 

 mature stage does not depend on the size of the speci- 

 men; it may be found in small and large forms. In 

 small specimens with a bulla-like final chamber (pi. 27, 

 fig. 16b) the Globigerina stage may be missing. 



Globorotaloides, new genus, differs from Globorotalia 

 in the interiomarginal umbilical position of the primary 

 aperture in the final chamber and in the possession of a 

 bulla-like small chamber that covers part or all of the 

 umbilicus. 



It differs from Globigerina in having an early Globoro- 

 talia stage and a buUa-like small final chamber. 



Globorotaloides resembles Catapsydrax in having a 

 bulla-like small final chamber but differs La having an 

 early Globorotalia stage. 



Globorotaloides suteri BoUi, new species 



Plate 27, Figures 9a-13b 



Shape of test low trochospiral, biconvex; equatorial 

 periphery lobate, in small specimens slightly elongate; 

 axial periphery rounded. Wall calcareous, perforate, 

 surface finely canceUate. Chambers ovate to spherical; 

 about 11-14, arranged in 2-2)2 whorls; the 4-5 chambers 

 of the last whorl increase fairly rapidly in size. Sutures 

 on spiral side slightly curved to radial, depressed; on 

 umbilical side radial, depressed. Umbilicus fairly wide, 

 open in immature specimens, in mature specimens 

 partly or completely covered by bulla-like chamber. 

 Aperture a slit or low arch ; interiomarginal, umbilical- 

 extraumbilical in early stage, later becoming interio- 

 marginal, umbilical, which in mature specimens becomes 

 covered by a buUa-like chamber with usually one, rarely 

 two or more infralaminal apertures. Coiling random 

 or some predominance for dextral. Largest diameter 

 of holotype 0.35 mm. 



Stratigraphic range (in Cipero formation): Most 

 common and typical in the Globigerina ampliapertura 

 zone, ranging to the Globigerinatella insueta zone. 



Locality: Holotype (USNM P5654) and figured 

 paratypes (USNM P5655a-d) from the Globigerina 

 ampliapertura zone, Cipero type section, Trinidad, 

 sample Bo 314A (TTOC 215658). 



Remarks: Globorotaloides suteri, new species, is dis- 

 tinguished from G. variabilis, new species, by the more 

 inflated early chambers, less curved sutures and fewer 

 chambers. 



The species is named for Dr. H. H. Suter in recogni- 

 tion of his contribution to the geology of Trinidad. 



Globorotaloides variabilis Bolli, new species 



Plate 27, Figures 15a-20c 



Shape of test low trochospiral, biconvex; equatorial 

 periphery lobate, in small specimens somewhat elongate ; 

 axial periphery subacute in immature specimens, 

 rounded in mature specimens. Wall calcareous, perfo- 

 rate, surface very finely canceUate. Chambers sub- 

 angular to ovate in early stage, later becoming ovate to 

 spherical; about 15-18, arranged in 2-2K whorls; the 

 5-7 chambers of the last whorl increase fairly rapidly 

 in size. Sutures on spiral side distinctly curved in 

 early stage, later becoming more radial, depressed; on 

 umbilical side slightly curved in early stage, later 

 becoming radial, depressed. Umbilicus fairly wide, 

 open in immature specimens, in mature specimens 

 partly or completely covered by a bulla-like chamber. 

 Aperture a slit or low arch; interiomarginal, umbUical- 

 extraumbilical in early stage, later becoming umbilical, 

 which in the mature stage becomes covered by a buUa- 

 like chamber with one infralaminal aperture. Coiling 

 random. Largest diameter of holotype 0.45 mm. 



Stratigraphic range (in Cipero and Lengua forma- 

 tions) : Globorotalia fohsi barisanensis zone to Globoro- 

 talia menardii zone. Most typical and common in the 

 Lengua formation. 



Locality: Holotype (USNM P5657) and figured 

 paratypes (USNM P5658a-e) from the Globorotalia 

 menardii zone, Lengua formation, road cutting, Concord 

 area, Pointe-a-Pierre, Trinidad, sample Rz 502 (TTOC 

 65629). 



Remarks: Globorotaloides variabilis, new species, is 

 distinguished from G. suteri, new species, by having 

 more compressed early chambers, more curved sutures 

 and a greater number of chambers. It is likely that 

 G. suteri, which is restricted to the lower and middle 

 part of the Cipero formation, is the ancestor of G. 

 variabilis, new species. 



Family Globorotaliidae Cushman, 1927 



Genus Globorotalia Cushman, 1927 

 Globorotalia opima opima Bolli, new species, new subspecies 



Plate 28, Figures la-2 



Shape of test very low trochospiral; equatorial 

 periphery slightly lobate; axial periphery rounded; due 



