492 MESSES. WHITAKER AND JUKES-BROWNE ON [Aug. 1 894, 



particles in the greyish-brown stone are not oolitic, but seem to be 

 merely organic fragments stained by oxide of iron ; many are friable 

 and break away in the preparation of the slice, leaving empt}' spaces 

 with a ferruginous lining, but others remain and seem to be rolled 

 pieces of shell partially replaced by a yellow-brown mineral, pre- 

 sumably a decomposed glauconite. Others are stained black by 

 what may be manganese (it is not cubical pyrites). The grey stone 

 has less matrix and a greater number of organic fragments, some 

 rolled and some angular : besides echinoderm and molluscan shell 

 a piece of Terebratida- shell and a lattice-work fragment (? coral) 

 can be seen in the slide, which is traversed by a vein of calcite. 

 There are also some oval bodies which in shape resemble cyprid- 

 cases. 



12. A light-grey calcareous rock, bearing so close a resemblance 

 to the grey stone above described that it might be from the same 

 bed. Dr. Hinde, to whom a slice was sent, remarks that " it seems 

 to be mainly composed of plates and spines of echinoderms, prob- 

 ably sea-urchins, fragments of molluscan and entomostracan shell, 

 a few foramiuifera, and an occasional sponge-spicule, but I do not 

 recognize coral-structure in it. The foraminifera are principally 

 Textalaria, but there are specimens of another genus with perforated 

 walls." A few grains of quartz are scattered through the slide. 



Mr. Hill remarks to us that the general assemblage of organic 

 fragments and their arrangement is similar to that in some of the 

 raised coral-reef rock of Barbados. 1 



13. A hard, light greenish-grey, slaty rock, showing what seem 

 to be two sets of cleavage-planes : one of these slopes at an angle 

 of about GO ; the other forms jagged edges on the broken surface 

 of the block, and seems to be nearly parallel to the vertical face of 

 the core. The block was said to come from 638 feet. 



14. One from 647 feet is a mash-up of soft, grey, shaly rock 

 enclosing fragments of hard slate or argillite. Another from 650 

 feet is a dark-grey compact rock with white veins : this looked like 

 a limestone, but did not effervesce with acid and appears to be a 

 kind of hornstone or argillite with quartzose veins. A third 

 sample from 657 feet is a dark-grey slaty rock resembling some of 

 the imperfect slates or killas of Devon and Cornwall, but it might 

 equally well be of Cambrian or Ordovician age. 



Slides from several samples of these slaty rocks were made at the 

 Geological Survey Office, and were examined by Mr. Teall. One, 

 marked as coming from between 645 and 647 feet, is a fine-grained 

 siliceous stone of the lydianite or hornstone type and is traversed 

 by numerous white quartz-veins. Mr. Teall describes it as composed 

 of minute crystals of quartz, felspar, white mica, brown mica, and 

 chlorite, the first two minerals predominating. 



Another, labelled as " shale 657 feet," he describes as composed 

 of exceedingly fine particles — amongst which a few grains of quartz 

 and scales of mica may be recognized. 



1 See Quart. Journ. Geol. Soc. vol. xlvii. (1891) p. 244, and pi. ix. fig. 4. 



