I«0 NEW YORK STATE MUSEUM 



these cross sections do not represent Globigerina, but Textularia 

 globulosa forms which are very abundant as well. In the latter 

 case, however, they would be very minute and the septal division 

 distinct and marked by almost straight septal lines between each 

 series. Moreover the segments in Textularia should be of equal 

 size. 



The large forms ascribed to Globigerina with but two segments 

 symmetrically developed and of unequal size belong to the above 

 species. The two-lobed Globigerina in which the segments are 

 of equal size and often with affluent chambers belongs to the 

 G. didyma of Matthew. One example on slide i measures 

 0.2I mm and has well-defined walls with chambers confluent at the 

 center, which would not hold true for T. globulosa Ehrenberg 

 cut on end. The G. bilobata are generally smaller than 

 G . didyma Matthew. 



Globigerina buUoides d'Orbigny 



Plate 4, figures i6, 17 



Globigerina bulloides d'Orbigny, 1826, Ann. Sci. Nat., 7:277 



No. I : Module, no. 76 and young no. 17 

 Globigerina b u 11 o i d e s Cushman, 1918, U. S. Geol. Survey Bui. 



676, p. 12, 32, 56, 79, pi. iii, fig. 2; xii, figs. 4, 6 



The most abundant of all Globigerina found in these cherts belongs 

 to the above species. It is especially well developed on slides 1,3, 

 5 (X) and 6. The diameter of these specimens varies widely, partly 

 due to the various angles at which the sections are cut. The walls 

 are well developed and occasionally relatively thick, and the limits 

 of the forms measured varied from o.ii mm to above 0.21 mm 

 across the entire specimen. Very few cross sections would of course 

 reveal the entire segmentation of a rotaline spiral form like Globi- 

 gerina, even though it were relatively depressed at the apex. 

 The more widespread, angular chambered types belong to G. 

 cretacea d'Orbigny, but these are not very frequent in any 

 of the sections examined. 



Globigerina bulloides var. Triloba Reuss 



Globigerina triloba Reuss, 1849, Denks. Akad. Wiss. Wien, i :374, 

 fig. II 



Several trilobed Globigerinae occur in the cherts but they differ 

 from Globigerina bulloides d'Orbigny only in possess- 

 ing three segments and we have therefore omitted illustrations 



