No. 5.] DAWSON — FORAMINIFERA, MANITOBA. 



255 



The common spiral Foraminifer in the Pembina Mountain 

 specimens, is Discorhina (^Rofalia) glohularis, D'Orb. sp., and 

 is probabl}^ identical with Rotallna {Rotalia) glohuJaris, cha- 

 racteristic of and very common in the upper and lower chalk of' 

 England. This form is also common in the specimens from- 

 Nebraska, and must be the same as Planorhulbia ghhidosa^ 

 recognized by Parker and Jones from Ehrenberg's figures as 

 occurring in the Mississippi Cretaceous.^ These authors there 

 remark that FlanorhuUna glohulosa, Ehr. sp. "must not be 

 regarded as worth much, being a very minute Rotaline, and 

 such a form as sevenil species might present in their earliest 

 stage of growth." It forms, however, a well marked type 

 in the Manitoba and Nebraska deposits, and as no larger 

 examples occur, must be regarded as an adult though depau- 

 perated variety. It is common everywhere at the present day. 

 In the North Atlantic it is best developed from the shore down to 

 50 or TO fathoms. It becomes flatter at greater depths. The 

 specimens from Manitoba are considerably flattened. 



A second Rotaline, smaller and flatter than the rest, and with 

 more delicate chambers and more in a whorl, is referable to 

 Pkuiorbulhia (^Planulina) ariminensis, D'Orb. sp., included 

 under P.farcta by Messrs. Parker and Jones, and belongs to 

 the series of small quasi Rotallan and Nautiloid forms, more or 

 less symmetrical, which they state f to be very common in some 

 secondary depo.^its, and abundant in the present seas at from 

 100 to 1000 fathom^!. P. (iriminensis is common in the English 

 chalk, in that of Moon, Denmark, and doubtless elsewhere. It 

 is also found in Tertiary and recent deposits. Glohlgerince — 

 referable to G. cretdrra, also occur, and an examination of a 

 larger quintity of material than tliat now at my disposal would 

 no doubt bring to light many additiot'.al fdrnT^. 



The general f icies of tlie foraminiferal fauna of these Creta- 

 ceous rocks of Manitoba and Nebraska singularly resembles that 

 of the ordinary English chalk. Both abound in Textularine 

 and Rotaline forms of similar types, the most abundant in 

 both beins the form with globose chambers, and each haviuGT 

 its rarer analoiiue with chambers flattened and more delicate. 



To the bodies now included under the general name CoccolitliUj. 

 attention has only been prominently drawn of late years. Ehren- 



* Quart. Jour. Geol. Soc. 1872. 



t Memoir on Atlantic and Arctic Foraras. 



