from Southern Ni(/eri(i. 205 



the type of Discoci/clina, being- misinterpreted by Giinibel, 

 subsequent writers iiave deemed it necessary to introduce the 

 name of Orthophragmina in its place. 



Tiie IbllowiMo; genera recognized by Schlumberger (memoir 

 before quoted, 1901, pp. 463, 464) constitute the Orbitoidal 

 group of the Foramiiiifera as now understood: — 



(1) Orhitoides, Orbigny, with rhomboidal equatorial chambers 



augmented sensibly in height towards the circum- 

 ference, where they are frequetitly subdivided ; perfo- 

 rations of the septa rather strong. 



Ty'pe= Orbitolites media, Archiac. 



Fcrnuvion and Localities, Upjier Cretaceous (Dor- 

 donien) of Franc3j &c. 



(2) Orthophragmina, Munier-C/halmas, with equatorial cham- 



bers " parall^lipddiques," = square or rectangular. 



Tv[)e= Orbitolites pratti, Michelin. 



Fonn'ttion and Localities. Eocene to Oligocene 

 (Priabonian), Biarritz, North Italy, Kressenberg, &c. 



(3) I^opidocyclina, Glimbel, with rounded or hexagonal 



equatorial chambers, and with finely perforated septa. 



'Yy'^Q,=.Nammulitcs mantelli, Morton. 



Formation and Localities. Oligocene (Vicksburg 

 Group), N. America, and Miocene of Europe. 



(4) Myogypsina, Sacco, with spiral embryo more or less 



excentric and lanceolate equatorial chambers. 



'\^y^it = JSummulites irregularis, Michelotti. 



Formation and Looalities. Miocene (Aquitanian), 

 Italy, &c. 



The main organisms of this limestone and those only tliat 

 can be seen in a general way without microscopical aid are of 

 abundant occurrence, being trequently closely packed together 

 in layers, and resembling in this manner some rocks from 

 Biarritz and Kressenberg containing Orthophragmina p^ratti 

 [ = papyracea of Gumbel, non Boubee) of Eocene age. 



Tiie specimens also agree in being of nearly the same 

 diameter, probably rather smaller, and also in their excessive 

 thinness — so much so, that horizontal internal views are 

 difficult to obtain. 



Some excellent sections have, however, been mads by 

 Mr. Richard Hall, the Senior Formatore of the British 

 Museum (Natural History), which exhibit chiefly vertical 



