248 Proceedings of the Royal Physical Society. 



ledge serves me, has been found in a somewhat unusual 

 situation. 



I am sorry to say I have not been able to furnish myself 

 with all the information I could desire, as the friend from 

 whom I received the specimen is again in Turkey, and I have 

 consequently been prevented from communicating with him. 

 The specimen was found with others in great abundance in 

 spherulitic segregated masses in the Lower Silurian rocks, 

 embedded — and in the opinion of several geologists who 

 examined specimens in situ, they had either been segregated 

 from surrounding rocks, or they were metamorphosed coproli- 

 tic masses. The latter supposition is however improbable, as 

 I can find no trace of organic structure in them, besides all 

 the specimens have a spheroidal structure, and are each 

 distinct from the other. 



They were found on the banks of the Dniester. A small band 

 of Lower Silurian rocks extends for a short distance on either 

 side of the river, and it is in these rocks they are embedded. 



On referring to the Quarterly Journal of the Geological Society 

 for August 1875, 1 found a paper by Messrs Davies and Hicks, 

 in which they describe a form of phosphorite found above the 

 Bala Limestone. This form was also found in concretionary 

 masses, but was compact and not fibrous as the one is which 

 I now exhibit. Dr Voelcker's analysis showed 40-60 % of 

 tricalcic phosphate. They had fragments of Lingula in their 

 structure, and are undoubtedly of organic origin. 



A short time since Professor Dawson described the occur- 

 rence of phosphorite in the Cambrian rocks of Canada, but 

 they differ in several points from the form I show you. 



I made an analysis of a piece of the fractured portion, which 

 was as follows : 



Loss on ignition, ..... 



Lime, ....... 



(P2O5) Phosphoric anhydride (= Trical. Phosp. 78-87), 

 Oxide of iron, ..... 



Magnesia, ...... 



Silica, ...... 



Alumina (Cog), etc., ..... 



100-00 



