1/2 NEW YORK STATE MUSEUM 



Many figures of this species indicate considerable variation both 

 as to the number of chambers — usually from three to five, never 

 very many — and also, what is more significant, as to the mucronate 

 character of the primordial chamber. This is not, however, a 

 cDnstant character, and in cross sections such a feature would not 

 appear unless the test were cut near the center. 



This shell occurs today in the North Atlantic at depths of from 

 300 to 1360 fathoms, in the South Pacific from 125 to 1350, and it 

 is reported from many localities outside the tropics. Geologically 

 it has been reported from earliest Trias but is especially developed 

 in Cretaceous formations. 



The figure shown by Reuss as D. globifera is an excellent 

 type but it has too many segments (twelve in the figure) for the 

 Precarboniferous varieties. We find several sections, perhaps some 

 fragmentary, of this species in the cherts before us. The best 

 perhaps are those with five segments shown on slide i and on slide 6. 

 Other examples are shown on slides 2 (figure 18) and 4. 



Genus CRISTELLARIA Lamarck 



Cristellariae are rare and doubtfully represented in the Bona- 

 venture cherts, but two species seem to occur. The difficulty 

 of identification lies in the fact that the aperture does not show in 

 the cross sections found, and these must be present on the outer 

 margin if the form were cut in a median line. The genus goes 

 back to the Cambrian but does not seem ever to be a well-developed 

 type until the beginning of the Trias. The earlier types are not 

 involute but are well represented by a few-chambered, curved form 

 which we identify as C. acutauricularis (Fichtel & Moll) 

 described below. 



Cristellaria acutauricularis (Fichtel & Moll) 



Plate 3, figures 20, 21 



Nautilus a c u t a u r i c u 1 a r i s Fichtel & Moll, 1803, Test. Micr., 



p. 102, pi. xviii, figs, g-i 

 Cristellaria acutauricularis Chapman, 1900, Quar. Jour. Geol. 



See, 56:259, pi. XV, fig. 9 



Mr Chapman says of this form "In outline the Cambrian specimen 

 resembles a cristellarian of the C. acutauricularis type ; 

 but the chambers are remarkably few in number, there being appar- 

 ently only four in the specimen under notice." This form came 

 from the Upper Cambrian of the Malverns. On slide 3 we find a 



