REPORT OF THE DIRECTOR I918 181 



of this subspecies. All forms placed here are much smaller than 

 the coarsely built, large and irregular, three or four-lobed Globigerina 

 identified as Globigerina cambrica Matthew. 



Globigerina cambrica Matthew 



Plate 4, figures 18, 19a, b 



Globigerina cambrica Matthew, 1895. Trans. N. Y. Acad. Sci., 

 14; iii, pi. i, figs. 5a, 5b, 5c and 6 (G. g r a n d i s) 



Several multilocular, but irregular, Globigerinae closely related 

 to trilobate Globigerina bulloides were described by 

 Matthew as new species. The irregularity of segmentation as com- 

 pared with typical G. bulloides serves to help differentiate 

 these primitive few-chambered forms from those inhabiting recent 

 oceans. On slide i is a Globigerina which seems to belong to this 

 type. Another is found on slide 2. 



Globigerina cretacea d'Orbigny 



Plate S, figures 4, 5a, b 



Globigerina c r e t a c e a d'Orbigny, 1840, Soc. Geol. France, Mem. 



1st ser., 4:34, pi. 3, figs. 12-14 

 Globigerina cretacea Woodward & Thomas, 1884, (1885) 13th Ann. 



Rep't Geol. Survey Minn., p. 171, pi. ii (D), figs. 18, 19 

 Globigerina cretacea Cushman, 1918, U. S. Geol. Survey Bui. 576, 



p. 56, pi. xiii, fig. 3 



Globigerina cretacea represents a widespreading, multi- 

 chambered Globigerina in which the final whorl contains not less 

 than six and often several more segments. These chambers when 

 cut in sections tend to angularity within, and this is especially true 

 on the inner chambers. ■ This same feature is sometimes revealed 

 in Rotalia, but in the latter the walls possess interseptal canals such 

 as are never found in this genus. 



One of our specimens shown in slide i has twelve segments, seven 

 of which are in the final convolution. The spherical segments 

 shown above may not represent the entire number originally present ; 

 but, they can not be far from that, and the section must have been 

 cut near the median line of the shell. G. cretacea is not well 

 known in existing oceans, but best belongs to the Chalk formation. 

 We have identified it in the Cretaceous of New Jersey and the 

 Maryland Miocene, and Cushman's specimen was from the same 

 horizon. Burrows, Sherborn & Bailey record it from the English 

 Red Chalk but we do not find it recorded from any horizon earlier 

 than the Cretaceous. I think we are correct, however, in the 

 identification of this species in the chert material. 



