295 
1914-15.] Chalk Boulders from Aberdeen, etc. 
species recorded have not been found at less depth than 390 fathoms, and 
nearly all occur in very deep as well as shallow water. Yet amongst these 
are Textularia conica, “ living in shallow water amongst the coral reefs of 
the Tropics,” and Truncatulina 'proecincta, another coral reef species, 
though it has been found in 225 fathoms. Of Nonionina depressula 
Dr Brady remarks, “ The home of this species is on bottoms of less than 
50 fathoms.” 
The assemblasre as a whole is characteristic of the chalk north of the 
o 
Wash rather than that of southern England.^ Bulimina, Textularia^ 
Gaudryina, and Tritaxia, the most abundant forms of the south, are rare. 
The Textularians recorded are very small specimens. Globigerinse are 
abundant in many specimens of the Belhelvie chalk, and in some of the 
sections are exceptionally numerous. Ammodiscus incertus also occurs in 
many of the residues. 
I am indebted to Mr Herbert H. Thomas for the identification of the 
mineral grains. Mr Thomas remarks, “ All the quartz of these chalks 
appears to be primary and contains the usual inclusions of detrital quartz ; 
there is no evidence of secondary growths. The most striking feature 
of the residues seems to be the relatively high percentage of felspar 
and the paucity of some of the heavy minerals such as zircon, rutile, and 
tourmaline, which are usually common in sedimentary rocks. All the 
minerals mentioned above have been recorded by Dr Fraser Hume and 
others from the English Chalk, but Dr Hume states in the case of the 
* See “ The Cretaceous Rocks of Britain,” Memoir of the Geological Survey, vol. ii, 1903, 
pp, 286 and 309. 
