184 NEW YORK STATE MUSEUM 



for their identification some are cut on edge and reveal the true 

 plano-convex outline, especially such as in T. 1 o b a t u 1 a . 



I do not think this genus has ever been found in the Cambrian 

 although Truncatulina lobatula must certainly be 

 expected, since we have the higher genera, Pulvinulina and Rotalia, 

 in deposits of this period. It has been described from the Carbon- 

 iferous of Europe where several species occur; it is known in every 

 horizon from that era and is one of the most widely known forms 

 in the seas of today. It is moreover found not only in all seas, 

 but down to greatest depths and in all sorts of deposits from shore 

 sands to the radiolarian oozes of the Pacific abysses. It is not 

 possible to establish the genus in every cross section, for Discorbina, 

 Pulvinulina, Rotalia and the like resemble this genus in transparent 

 outline. In the cherts we find Truncatulina well preserved, of good 

 size with well-developed, numerous septa, and in all respects identical 

 with forms existing at the present time. 



Trunpatulina boueana d'Orbigny 



Plate s, figures 8, 9 



Truncatulina boueana d'Orbigny, 1846, Foram. Foss. Vienne, 



p. 169, pi. ix, figs. 24-26 

 Truncatulina boueana Brady, 1876, Pal. Soc, 30: 139, pi. vi, fig. 11. 



Truncatulina boueana d'Orbigny is often included 

 under the synonyms of T. lobatula, and we have ourselves 

 so written it. The distinction, however, has been made, and can 

 be, for those few-chambered forms consisting of but nine segments, 

 as shown in the original description and figure. In slide i we find 

 a good example of such a type. There are seven segments present 

 in the final whorl and part of the eighth, the primordial chamber 

 not being visible. The outer periphery is slightly lobed, but it 

 has been etched and eroded away on several segments. The septa 

 are somewhat more straight than in the type figures and in this 

 respect it approaches Pulvinulina micheliniana. As- 

 Pulvinulinae have as a rule less segments than most rotalian forms, 

 it is not impossible that this form .is P. micheliniana. 

 Truncatulina is, we believe, more apt to develop in earlier horizons 

 than Pulvinulina of higher organization. The less arched septa 

 are also more characteristic of Truncatulina than true Rotalia, 

 Pulvinulina, or Discorbina types. 



The diameter is o.io mm in the maximum and 0.08 mm in the 

 smallest of the specimens. This species must not be confused 



