﻿534 Henry B. Brady — Notes on Cretaceous Foraminifera. 



favour of the rock being regarded as chalk are that physically it is 

 almost indistinguishable from most typical specimens of that rock, and 

 that it has had the same organic origin; the Foraminifera alone are not, 

 unfortunately, sufS.cieut to rigidly determine the geological age of the 

 rock, because they are types which have been persistent from the 

 Cretaceous period to the present time. 



II. — Supplementary Note on the Foraminifera of the Chalk (?) 



OF THE New Britain Group. 



By Henry B. Brady, F.R.S., Etc., Etc. 



SINCE writing the letter quoted in the foregoing communication 

 by my friend Prof. Liversidge, I have had the opportunity of 

 examining a larger fragment of the calcareous rock to which it 

 refers, and am thereby enabled to add somewhat, not merely to the 

 list of Foraminifera which it contains, but also to the general con- 

 clusions to be drawn from it. The lithological characters of the 

 rock are, as Prof. Liversidge has stated, precisely those of many 

 specimens of white chalk, but it is seldom that a Cretaceous mineral 

 is so entirely composed of the recognizable remains of microzoa, and 

 it is still more rarely that a geological deposit occurs, for which so 

 exact a counterpart in process of formation can be indicated. Under 

 these circumstances some further remarks on the subject may not be 

 without interest. 



The following is a revised list of the Foraminifera, with notes 

 appended concerning a few of the less generally understood species : 



Globigerina bulloides, d' Orbigny. 



inflata., d' Orbigny. 



Dutertrei, d' Orbigny. 



saecidifera, nov. 



{Orbulina) universa,<i'Ox\)ignj. 



Sphmroidina buUoides, d'Orbigny. 



dehiscens, Parker and Jones. 



Pulvmulina Ilenardii, d'Orbigny. 



var. tumida, nov. 



pauperata, Parker and Jones. 



favus^ nov. 



Rotalia Soldanii, d'Orbigny. 



Nonionina umbilicatula, Montagu. 



•— — — — pompilioides, Eichtel and Moll. 



Spiroloculina celata, Costa. 

 Lagena marginata, Montagu. 



Icevis, Montagu. 



apiculata, Keuss. 



• aspera, Eeuss. 



Dentalina brevis, d'Orbigny. 



communis, d'Orbigny. 



obliquestriata, Reuss. 



Vaginulina legumen, Linne. 

 JJvigerina asperula, Czjzek. 

 Bulimina Buchiana, d'Orbigny. 

 CassiduUna crassa, d'Orbigny. 

 Gaudryina pupoides, d'Orbigny. 

 FuUenia sphmroides, d' Orbigny. 

 ■ compressinscula, Reuss. 



This category, though considerably extended, by no means ex- 

 hausts the material, for it contains, in addition, certain species of 

 PlanorbiiUna and Truncatidina, which I have not as yet been able 

 to identify, besides fragments of Nodosarians, and some other obscure 

 organisms. 



Spiroloculina celata, Costa. — This naiiie is adopted in the absence 

 of a better for a species not uncommon in deep-water dredgings, 

 both from the Atlantic and the Pacific. The test is composed of a 

 uniform very fine sand, without any basis of calcareous shell ; the 

 sutures are scarcel}^ discernible on the exterior ; the aperture small 

 and obscure, sometimes apparently wanting-. It diflers from the 



