REPORT OF THE DIRECTOR I918 189 



specimen; but there are three volutions or whorls visible, and under 

 different focusing one can determine their general position. The 

 shell wall is prismatic and thick, closely like the nummuline structure 

 of Pulvinulina partschiana, shown on page 700 of 

 the Challenger Report, volume 9, but the chambers are more circular 

 than this type shows. Brady in his Challenger Report does not 

 attempt to separate these two species ; but considers P . part- 

 schiana a smaller, more convex, thinner walled form than 

 P. elegans, and adds that P. elegans occurs more often 

 in shoal waters while P. partschiana is usually a deep water 

 form. On the other hand, he considers P. elegans more typical 

 of warm waters, though occurring with its congenitor in all oceans. 



Goes identified P. elegans in waters of the Arctic ocean and 

 states that it is rare at 1750 meters. As a fossil it is better known 

 than P. partschiana. It occurs from the Trias through 

 succeeding formations, but is perhaps better known as a Cretaceous 

 type. 



The vertical transverse section we are describing measures 0.15 

 mm in length (diameter) and 0.07 mm through the cone apex. It is 

 very probable that this form occurs in some of our rotaline cross 

 sections; but, if so, they are difficult to identify or separate from 

 other Pulvinulinae which we know occur in these cherts. 



Pulvinulina micheliniana d'Orbigny 



Plate 6, figures 7, 80, 6, c 



Rotalina truncatulinoides d'Orbigny, 1839, Foram. Canaries, 



p. 132, pi. ii, figs. 25-27 

 Rotalina micheliniana d'Orbigny, 1840, Mem. Soc Geol. 



France 4:31, pi. iii, figs. 1-3 

 Pulvinulina micheliniana Parker & Jones, 1865, Phil. Trans., 



155:396, pi. xiv, fig. 16 



A peculiar diagonal cross section of a form on slide i seems to 

 belong to this species, but it is somewhat uncertain owing to 

 the fact that not all segments are visible. The center chambers 

 are perfect and distinctly rotaline; but the outer margin seems 

 to be somewhat disconnected or discontinuous from these, which 

 show on a vaulted and highly thickened wide margin a high and 

 sharp edged spire. It is possible that this form is Truncatu- 

 lina refulgens (Montfort) which is the isomorph of the 

 Pulvinulina type ; but from the thickened border and highly invo- 

 lute and many segmented inner whorls, I think it is more likely to 

 be Pulvinulina than Truncatulina. If the indefinite and vaulted 



