222 MINERALS AND GEOLOGY 



ing pseudopodia* ; and 4, Radiolaria with siliceous, highly foramin- 

 ated test as regards the more typical forms. 



Remains of Foraminifera, all belonging to living species, were 

 detected some years ago in the leda clay formation (immediately 

 above the true drift deposits, see Part Y.) by 

 Sir J. "W. Dawson in the vicinity of Montreal, 

 and at Beauport, near Quebec. The most com- 

 mon form is the Polystomella (or Nonionina ?), 

 shown at B in the following highly magnified 

 figure. Another, but much less common form, 

 from Beauport, observed by the writer in some 

 B Poiystsmeiia (or No- sandy matter in the interior of a fossil balanus, is 

 t shewn at A. It is a species of Textularia : a living 

 Ulis?). genus, dating from the Carboniferous epoch. 



In addition to these essentially microscopic forms found in our 

 post-cainozoic deposits, some comparatively gigantic types, referred 

 rightly or wrongly to the foraminifera, have been discovered in our 

 Archaean and Palaeozoic (Cambrian and Lower Silurian) rocks. 

 These comprise, chiefly, the Eozoon of Dawson, the Archceocyathus 

 and some related forms together with the Pasceolus of Billings, and 

 the Receptaculites of Ferdinand Roemer. The true nature of these 

 fossil forms, however, is exceedingly obscure. The Eozoon is 

 regarded by Mobius, King, and other high authorities, as entirely of 

 inorganic origin, notwithstanding the able memoirs of Dawson and 

 Carpenter in defence of its assumed foraminiferous character. It 

 occurs, with us, in the crystalline Lauren tian strata of North 



The Foraminifera may be sub-divided, practically, as in the following synopsis : 

 GROUP I. Imperforata : Body -covering or shell with single external opening for passage of 

 pseudopodia. 



1. Chitonosa : With chitonous (or indistinct) bod)' -covering : 



Fam. 1. Gromidce(e.g., Gromia, Lieberkiihnia). 

 2. Arenacea : With body-covering made up of agglutinated sand-grains, &c. 



Fam. 2. Lituolidce (e.g., Lituola, Saccamina'K 

 3. Porcellanea : With calcareous, non-foraminated, porcelain-like shell. 



Fam. 3. Miliolidce. (e.g., Cornuspira, Miliola, &c.). 

 GROUP II. Perforate/, : with distinctly foraminated shell : 



4. Vitrea : Shell more or less distinctly hyaline ; calcareous ; foraminated : 



Fam. 4. Lagenidce: Shell with very minnte foramina (e.g., Lagena, Cristel- 



laria, &c.). 

 Fam. 5. Globigerinidce : foramina comparatively large; shell thin (e.g., 



Textilaria, Globigerina, &c.). 



Fam. 6. Nummulinidce : foramina comparatively large ; shell solid (e.g. , 

 Nummulina, Fusulina, &c.). 



