360 MR. A. STRAHAN ON A PUOSPHATIC 



treatment with acetic acid. They are of all shapes, but all sharply 

 angular, and range from '1 mm. to 1 mm. in length. 8ome consist 

 of alternate bars of clear and cloudy material, the lactcr resembling 

 the substance which fills the phosphatized foraminifera, while the 

 clear portions show change of colour when rotated between crossed 

 nicols. In a large number of even the smallest chips Dr. Hinde has 

 been able to recognize bone-lacunae, while some are fragments of 

 fish-scales. A few have been identified by Mr. E. T. Newton as 

 fragments of fish-teeth, the canals and lacunae appearing as dark 

 tubes penetrating the amber-coloured material. Other irregular 

 markings seem to be the borings of fungi, as was suggested to me 

 by Dr. Hinde. There seems to be no reason to doubt that the 

 smaller chips, in which no recognizable markings occur, are also 

 fragments of either the teeth or bones of fish *. 



Several of the amber-coloured grains were picked out and treated 

 with strong nitric acid under the microscope. A few dissolved 

 without effervescence, but a larger number with effervescence, the 

 action being especially brisk in the cloudy portions ; the solution 

 gave as copious a yellow precipitate with ammonium molybdate as 

 the foraminifer and prism referred to above. This result was con- 

 firmed by the following test made by Mr. A. Dick: — Three trans- 

 parent grains, on treatment with dilute sulphuric acid, became opaque 

 with slight effervescence; the solution was evaporated nearly to 

 dryness and a drop of water added. The clear liquor was then led 

 oft' to another part of the slide and a drop of magnesia-liquor added, 

 when the characteristic crystals of the phosphate of magnesia and 

 ammonia were formed. When treated with dilute sulphuric acid 

 the grains yield crystals of sulphate of lime. Erom these tests it 

 may be inferred that the amber- coloured material consists essen- 

 tially of a mixture of carbonate and phosphate of lime. 



Lastly, the oval pellets retain their shape and appearance afrer 

 treatment with acetic acid t- They range from -3 mm. to '9 mm. 

 in length, and from '2 mm. to '4 mm. in thickness. A few show 

 transverse markings which resemble those attributed in larger 

 coprolites to spiral folds in the intestine. When broken across 

 they not unfrequently disclose a darker central portion of indefinite 

 outline, but no clear internal structure. There seems no reason to 

 doubt that they are the excrement of small fish, plenty of which occur 

 in the Upper Chalk. Dr. Hinde, who has given me much assistance 

 in the investigation of these bodies, points out that they correspond 

 in shape to bodies found by him in association with fish-remains 

 in the interior of a chalk-flint. 



Before leaving this part of the subject, I may remark that fish- 

 remains, whether in the form of pellets or angular bone-chips, are 

 abundant in all thephosphatic chalks yet known, and may suggest that 



* Portions of a tooth of Cimolichth/s from the Chalk have yielded chips re- 

 sembhng tliose scattered through the Taplow Chalk, and gave the same reactions 

 •with chemical tests. 



t It is worth remarking that the pellets are easily sorted out by rolling the 

 whole of the washed brown grains down a smooth inclined plane. 



