176 NEW YORK STATE MUSEUM 



to the large, ultimate, elliptical segment, as would be the case with 

 this species. The formi is much larger than in the specimen of 

 P. compressa and measures 0.25 mm in length. The outline 

 is broadly oval with prolonged aperture, a little eccentric, and 

 shows but two well-defined chambers, the inner one more nearly cir- 

 cular and impressed against one side. 



Typical spscimens show more spherical shape than the one we 

 are describing, which is more like P. 1 a c t e a in some respects 

 than P . g i b b a . In the latter there is a different arrangement 

 of segmentation, and the form is more minute; but there are many 

 closely related types such as P. aequalis, P. lactea, 

 Globulina p u n c t a t a d'Orbigny, Globulina amplec- 

 t a n s Bornemann, and the variety G. orbicularis, as also 

 P. (Guttulina) deformata Reuss, the latter being some- 

 what similar to the type we are discussing. A few specimens on 

 other slides may belong to this type, but Polymorphina is a hard 

 genus to identify in cross section, as only the outline of segment 

 arrangement can be seen. 



P. g i b b a is known from the Trias of Europe and is found in 

 existing oceans. 



Genus ORBULINA d'Orbigny 



■ The genus Orbulina has been recorded from Cambrian strata of 

 New Brunswick, from the Devonian of Paffrath in the Eifel, in the 

 Trias of Bakony, and in every succeeding period; and is today 

 one of the most abundant . pela'gic species of every ocean. Nor- 

 mally there is no aperture in Orbulina, which makes the Orbu- 

 lina ovalis of Matthew from the Canadian Cambrian extremely 

 problematical. It is more likely that the form is Lagena instead; 

 but we shall follow Matthew and recognize this type, since in our 

 specimens no aperture occurs and the shell is not circular as 

 O. universa requires. 



We therefore with some reservation recognize both O. uni- 

 versa and O. ovalis in the cherts under investigation and 

 a still more problematical large form, O. p o r o s a . The last 

 is known in the Trias and is a large, stoutly built type. Today 

 Orbulina universa is a small form, with thin and delicate 

 shell wall. Our fossil specimens are large for the type, and not 

 all are truly spherical. 



