ME. H. B. BBADY ON SACCAMMINA CARTERI. 271 



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 that they form an intensely hard dark- 

 coloured limestone, the freshly fractured surface of which 

 appears almost homogeneous and sometimes subcrystaline. It 

 is, however, readily acted upon by the atmosphere, and the 

 weathered portions reveal a spheroidal structure that might at 

 the first glance be assigned to purely physical causes depending 

 on some peculiarity in the mode of deposit. A fair idea of the 

 characters of the rock forming this bed may be gained from 

 Plate XL, fig. 1, which represents an average specimen, with 

 the upper surface considerably weathered. Very frequently the 

 disintegration, instead of being merely superficial as in the 

 figured specimen, extends to a considerable depth, leaving the 

 stone in the condition of a crumbling mass of spheres. A layer 

 in this state exists between the surface-soil and the hard rock, 

 and by a little treatment the fossil portions may be obtained 

 from it quite clear of the matrix. 



A few feet below this bed (in the same section), and separated 

 from it by a thin layer of shale and a stratum of limestone con- 

 taining Bryozoa, is a second and more considerable bed, with 

 the same sort of fusiform bodies distributed through its entire 

 length and thickness. The individual specimens are larger than 

 those occurring in the later deposit, but they do not constitute 

 nearly so considerable a proportion of the entire rock. The 

 segments do not appear to differ in structural characters from 

 those found in the upper bed. 



Mr. Topley, of the Geological Survey, has furnished me with 

 a rock specimen from another section in the neighbourhood of 

 Elfhills, but at some distance from the main quarry. The point 

 from which it was taken is apparently about sixteen feet higher 

 in the series than the top of the quarry. This may perhaps 

 only be the upper bed, faulted. It immediately overlies one of 

 the branches of the whin-sill, and seems to have been a good 



