l62 NEW YORK STATE MUSEUM 



depressed margins and few segments, as often seen in 

 B. pupoides. There are no distinct intermediate segments 

 such as I should expect in triserial types, but the irregularity, the 

 general contour and disposition of segments seem to justify the 

 placing of this specimen under a true Bulimina and near B. 

 pupoides d'Orbigny. 



The species has been recorded in the Cretaceous of Minnesota; 

 but if the present determination is correct, the genus is present 

 in the Lower Paleozoic. 



Bulimina pyrula d'Orbigny 



Plate 2, figures s, 6 



Bulimina pyrula d'Orbigny, 1846, Foram. Foss Vienne, p. 184, pi. xi, 



figs. 9, 10 

 Bulimina pyrula (var. of Bulimina presli,) Parker & 



Jones, 1865, Phil. Trans., 155: 372, pi. xv, figs. 8, 9 



The section found on slide i near Pulvinulina miche- 

 1 i n i a n a (d'Orbigny) shows four or five segments in 

 unsymmetrical biserial development. The section is problematical, 

 but seems to represent this species, although we can not be positive 

 without further material for study. There are several reasons why, 

 however, this is probably correct. In the first place B . p y r u 1 a 

 has a long geologic history, being known from early Trias down 

 to the present, and is found in every horizon from the base of the 

 Mesozoic up. Again, this is a somewhat more simply built type 

 than the more elongate, triserial, overlapping forms of the Tertiary ; 

 and, third, two related subgenera are present in considerable 

 numbers. Furthermore, this species is of wide geographic range 

 today, and is known from shallow waters down to depths of nearly 

 3000 fathoms. 



Genus VIRGULINA d'Orbigny 



The genus Virgulina was founded by d'Orbigny to include those 

 intermediate forms between Bulimina and Bolivina. Bolivina is 

 biserial as in Textularia, but its aperture is a narrow arched slit 

 facing downwards and situated at or just below the distal margin. 

 In Virgulina and Bulimina it is often some distance below, and on 

 the inner face of the ultimate segment. In Bolivina the test is 

 symmetrical and biserial, while in Virgulina the shell elongation 

 often gives place to either very irregular, arched, biserial seg- 

 mentation, or it assumes a unicellular alternate growth something 



