270 MR. H. B. BEADY ON SACCAMMINA CARTERI. 



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

 of their zoological relationship. 



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

 mination of mineral veins and the adjacent rocks, were two or 

 three almost spherical bodies, one-twentieth of an inch in dia- 

 meter, somewhat produced at two opposite portions of their peri- 

 phery, and having a nearly smooth arenaceous exterior. In the 

 absence of material for a definite conclusion as to their nature, I 

 suggested that they were properly segments of a gigantic Lituola; 

 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 these spe- 

 cimens could not be determined with accuracy, much significance 

 was not attached to them ; but shortly after the presentation of 

 the paper referred to, my attention was directed by Mr. G. A. 

 Lebour, of the G-eological Survey, and Mr. Howse to a limestone 

 of somewhat unusual character occurring in the heart of North- 

 umberland. The specimen placed in my hands by Mr. Lebour 

 appeared to be made up almost entirely of spheres, which were 

 at once recognized as identical with those in Mr. Moore's col- 

 lection. 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 following notes embody the results arrived 

 at. 



Geological. — The bed from which the specimens were taken 

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

 and best-defined members of the Carboniferous Limestone series 

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

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

 way, it is quarried to a considerable extent, the stone being 

 burnt for agricultural purposes, and a section of from twenty 

 to thirty feet in height 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 (appar- 

 ently the overflow of a larger whin-sill) interbedded with it. In 



