a new Carboniferous Foraminifer. 181 



usually adhere by points to the interior of the shell ; so that 

 the siliceous casts are not only far more commonly met with 

 clear of the test than the calcareous, but they are also indivi- 

 dually heavicf. 



There is considerable difference in the appearance under the 

 microscope of the chambei's under different conditions of in- 

 filtration. Sometimes a sphere may be found partially filled 

 with silica and partially with carbonate of lime. A section 

 of such a one is shown at PI. XII. fig. 5. The lobe of silica 

 which occu})ies part of the right side of the chamber {a) is 

 amorphous, and has a yellowish tint by transmitted light, 

 whilst the remainder is calcareous and crystalline. Under 

 these conditions it is useless to attempt a comparison between 

 the chemical composition of the test of the fossil under con- 

 sideration and that of recent species of the same genus or 

 other allied arenaceous Foraminifera — a circumstance the 

 more to be regretted as the process of mineralization has also 

 obscured the minuter structm-e of the former so far as to pre- 

 vent accurate obscKvations on the nature of the sand-grains 

 and cement used in building its investment. 



Zoological. — To revert to the Elfhills specimens. The 

 subspherical bodies which constitute the mass of the rock 

 may be examined to some extent Ijy means of sections, but 

 far more completely and accurately by washing the marly or 

 crumbling mass resulting from partial disintegration by the 

 long-continued action of air and moisture. The residue after 

 washing this material consists chiefly of the arenaceous spheres, 

 fragments of Encrinites, and a few kindred fossils. The sphe- 

 rical or, rather, fusiform bodies average about g inch in length, 

 and ~ inch in transverse diameter : large specimens may be 

 found measuring ^ or even \ inch by \ or \ inch ; but such 

 are of rare occurrence. Sometimes they are more elongate ; 

 and extreme examples have been noted in which the conjugate 

 and transverse diameters were in the proportion of 3 to 1. 

 The two ends are usually produced and tubular, apparently 

 for the passage of sarcode stolons or pseudopodia : they are 

 sometimes symmetrical ; but more frequently one end tapers 

 more gradually than the other : occasionally the base is 

 roiuided, and the shape is completely pyriform. The question 

 arises whether these bodies represent individual animals, or to 

 what extent they ma;y have been connected with each other 

 when living. It is not at all unusual to find on any weathered 

 piece of the rock two segments connected by a stoloniferous 

 tube; rarely three are found in this condition; and in one or 

 two instances four or five have been noticed still retaining 

 connexion with each other. The bulk and weight of the 



