MARKER : NOTES ON NORTH OF ENGLAND ROCKS. 303 



be spines of an echinoid. The ground-mass of the rock, where not 

 recrystalHsed, is an iron-stained calcareous mud with pyritous specks. 



The interesting characters of the Yorkshire Kelloways rock have 

 been noticed by Dr. Sorby, and we may therefore pass on to the 

 higher calcareous members of the Middle Oolites. A specimen from 

 the 'Ball-be(is' of the Lower Calcareous Grit at Filey is crowded 

 with little sub-angular grains of quartz, while the matrix is so deeply 

 stained with iron-oxide that little or nothing can be seen [1023]. 

 There are, however, plenty of shell-fragments with a strong, slightly 

 oblique, lamellar structure, referable to Feden. Other specimens 

 would, no doubt, show other organisms. It will be remembered that 

 the Lower Calcareous Grit of Scarborough yields the little kidney- 

 shaped bodies, first noticed by Dr. Sorby, and recently shown by 

 Dr. Hinde to be the globate spicules of a siliceous sponge. 



In a slide from the ' Lower Limestone ' of the Filey Calcareous 

 Grit [1024], the most conspicuous fossil remains are wavy sections 

 of valves oi Rhynchonella tinirmanni. Brachiopoda are usually stated 

 to have shells composed entirely of calcite, but here the occurrence 

 within the lamellated calcite test of a zone of irregularly crystalline 

 calcite rather suggests that the shell had originally an inner layer of 

 aragonite. The other organic remains present are a few chambered 

 tests of foraminifera, joints of crinoid-stems, consisting each of 

 a single crystal of calcite, and calcite pseudomorphs after the 

 aragonite shells of lamellibranchs. Oolitic grains are seen, often 

 formed on a scrap of some organic substance. The general calcareous 

 matrix is for the most part crystallised on a minute scale, the 

 impurities being, as is usually the case, concentrated in particular 

 patches. 



The Middle Calcareous Grit, which forms the prominent feature 

 of Filey Brigg, presents i<t\v points of novelty [1025]. It is crowded 

 with little angular and sub-angular quartz-grains, containing either 

 glass- or fluid-inclusions. The next specimen is taken from the 

 ' Upper Limestones' of the same series [102 Srt-]. The slide shows 

 numerous sections of rather thick shells rep.aceti by an aggret^ate 

 of crystalline calcite, and apparently belonging to Trigonia. Other 

 shells, which have kept their original structure, must be referred to 

 Lima or Pecif.n. There are others, again, which seem to have had 

 layers of aragonite and calcite. Some scraps of shell with a trans- 

 verse fibrous structure probably represent entomostraca ; while 

 chambered foraminifera and remains of crinoids are also to be 

 detected. The quartz-grains which occur are rather angular. The 

 matrix is tolerably free from impurities, and the greater part of it has 

 recrystallised as a fine mosaic of calcite. 



Oct. 1890. 



