178 Mr. H. B. Brady on Saccammina Carteri, 



or the alteration produced by the process of mineralization, 

 present serious obstacles to accurate study. 



Under these circumstances the discovery of Foraminifera of 

 a well-defined and easily understood type in the Carboniferous 

 Limestone is a matter of some importance ; and an additional 

 interest pertains to those about to be described, on the ground 

 of their zoological relationship. 



Amongst the fossils met with by Mr. Charles Moore in his 

 examination of mineral veins and the adjacent rocks, were 

 two or three almost spherical bodies, -J-^ of an inch in diameter, 

 somewhat produced at two opposite portions of their peripheiy, 

 and luiving a nearly smooth arenaceous exterior. In the absence 

 of material lor a definite conclusion as to their nature, I sug- 

 gested that they were probably segments of a gigantic Lituolu ; 

 and as such they were mentioned in the list of fossils appended 

 to Mr. Moore's report presented to the British Association at 

 the Exeter meeting in 1869. As the geological source of 

 those specimens coidd not be determined with accuracy, much 

 significance was not attached to tliem ; but sliortly after the 

 presentation of the paper referred to, my attention was directed 

 by Mr. CI. A. Lebour, of the Geological Survey, and Mr. Howse 

 to a limestone of somewhat unusual character occurring in the 

 heart of Northumberland. The specimen placed in my hands 

 by ]\Ir. Lel)our appeared to be made up almost entirely ol 

 spheres, which were at once recognized as identical Avith 

 tliose in Mr. ]\Ioore's collection. Through the kindness of 

 Sir Walter C. Trevelyan, on whose estate the limestone occurs, 

 and to whom its discovery is due, every facility has been 

 afforded for studying the structure of the rock ; and the fol- 

 lowing notes embody the results arrived at. 



Geological. — The bed from which the specimens were taken 

 is the so-called '' foiu'-fathom limestone," one of the thickest 

 and best-defined members of tlie Carboniferous-Limestone 

 series throughout the north of England. At Elfhills, a point 

 situated a mile or two west of Cambo, near the Wansbeck- 

 Valley railway, it is quarried to a considerable extent, the 

 stone being burnt for agricultural purposes ; and a section of 

 from 20 to 30 feet in heiglit is there exposed. This exhibits 

 beds of limestone varying somewhat in physical characters, 

 with one or two thin beds of shale, and an intruded mass of 

 whin, apparently the overflow of a larger whin-sill interbedded 

 with it. In some places the limestone is a good deal altered 

 by its proximity to the volcanic rock. 



The uppermost bed exposed in the quarry appears to be 

 entirely composed of spheroidal or fusiform bodies, but so ag- 

 gregated and infiltrated tliat they form an intensely hard dark- 



