238 Reports and Proceedings — 



where they were present, and the shell of some of the larger trilobites, 

 as now preserved, -contained as much as from 40 to 50 per cent, of 

 phosphate of lime. The analyses made by Mr. Hudleston and the 

 author of recent Crustacea proved that they also contain P 2 5 in very 

 considerable proportions. 



In the second part of the paper the author showed that where in- 

 trusive dykes had passed through or between the beds containing the 

 phosphate of lime, the beds for some distance on each side of the dykes 

 had undergone a considerable change. Scarcely a trace of the P 2 5 or 

 of the lime was now to be found in them, though it was evident that 

 before the intrusions into them had taken place, they, like the other 

 portions of the beds, had evidently contained both ingredients in con- 

 siderable proportions. It was well known that heat alone could not 

 separate P 2 5 from lime ; therefore he found it difficult to account for 

 this change in the character of the beds, unless it could be produced by 

 gases or watery vapour passing into them at the time the intrusions 

 took place. He thought it even probable that the dykes, which in 

 some parts are found to contain a considerable amount of lime and also 

 of P 2 5 , might have derived these, or at least some portions of these, 

 from the beds through which they had been forced, and which must 

 have been broken up and melted as they passed through them. There 

 are no contemporaneous tuffs known in Wales of earlier date than the 

 Llandeilo beds ; and he thought these dykes belonged to that period, 

 and that they were injected into the Lower Cambrian beds after from 

 8,000 to 10,000 feet of deposit had been superimposed. In an agri- 

 cultural point of view the author considered that the presence of so 

 much phosphate of lime in some of the series of beds must be a matter 

 of great importance ; and on examining the districts where these series 

 occurred, he invariably found the land exceedingly rich. 



Mr. Hudleston gave the results of the analyses made by him at the 

 request of Mr. Hicks. He found in a portion of dark grey flaggy rock 

 taken from close to a fossil 1*62, in a portion of black slaty rock contain- 

 ing trilobites, but in contact with trap, 0*11, in a portion of the shell 

 of a trilobite 17"05, and in the trap above mentioned 0-323 per cent, 

 of phosphoric anhydride. A lobster-shell dried at 100° C. gave 3 - 26, 

 an entire boiled lobster (undried) 076, and a boiled lobster without 

 shell - 332 per cent, of P 2 5 . If the analysis of an entire lobster be 

 correct, he estimated that a ton of boiled lobsters would contain about 

 17 lbs. of phosphoric anhydride. In the analysis of the shell of a 

 trilobite there appears to be a great excess of phosphoric acid, which 

 Mr. Hudleston thought must be due to substitution. 



2. " Note on the Structure of the Phosphatic Nodules from the top 

 of the Bala Limestone in North "Wales." By M. Hawkins Johnson, 

 Esq., F.G.S. 



In this paper the author described the appearances presented by 

 thin sections made from some of the phosphatic nodules and shales 

 described by Mr. D. C. Davies, F.G.S., in his recent paper. Tn both 

 nodule and shale he finds structure which he is inclined to identify 

 with sponge-structure ; but the mass also contains innumerable foreign 

 bodies, chiefly fragments of the shells of Mollusca and Crustacea, with 

 many irregularly ovate bodies that remind him of Coscinopora, and some 

 that may be sponge-spicules. The author enumerated fourteen nodular 



