THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[FOURTH SERIES.] 

 No. 39. MARCH 1871. 



XXI. — On Saccammina Carterij a neio For aminifer from the 

 Carhom'ferous Limestone of Northumherland. Bj Henry 

 B. Brady, F.L.S., F.G.S. 



[Plate XII.] 



Introductory. — l^otwithstanding the prominent place occu- 

 pied by the Mountain Limestone amongst the geological 

 formations of Great Britain (its geographical extent and its 

 enormous thickness), but little is known of the Foraminifera of 

 the earlier Carboniferous age. The organic remains of which 

 the calcareous beds are at times almost entirely composed 

 afford abundant evidence of their marine origin, and analogy 

 with other limestone strata would lead to the expectation that 

 Foraminifera would constitute an important part of their fossil 

 fauna ; yet were a catalogue drawn up representing the pre- 

 sent state of our knowledge of Carboniferous Invertebrata, the 

 whole of the subkingdom Protozoa would.be told off in a few 

 lines. Nor have we far to seek for the reason of our compa- 

 rative ignorance of the minuter fossils ; indeed we need hardly 

 look fm'tlier than the physical characters of the material form- 

 ing the beds to see where the cause of difficulty lies. The rock 

 of which they are composed is almost always exceedingly 

 hard and compact, sometimes even subcrystalline, and scarcely 

 ever admits of examination in respect of its Microzoa other- 

 wise than by means of transparent sections, which yield but 

 little reliable information. It is only here and there that 

 pieces can be met with soft enough to allow the se])aration 

 of their constituent fossils by washing or other mechanical 

 means ; and the cases are still rarer in which any chemical 

 process can be resorted to Avith advantage to the same end. 

 But possibly an even greater difficulty exists in the Microzoa 

 themselves. Tlie Rhizopoda, at least, either from natural de- 

 ficiency of marked cliaracters, the obliterating effects of time, 



Ann A; Mag. N. Hist. Ser. 4. Vol. vii. 13 



