3G6 MR. A. STRAHAN ON A PHOSPHATIC 



the phosphatic type in any of the pits around Taplow, as might 

 have been expected were there a transition from the one type of 

 chalk into the other. On the other hand, if the phosphatic chalk is 

 overlapped in every direction by Tertiary beds, there must be a more 

 rapid transgression than is known elsewhere in this part of England. 

 The scarcity and incompleteness of the sections, however, preclude 

 our forming a definite opinion as to the reason of our failure up to 

 the present to detect the deposit in other parts of the neighbourhood. 

 In conclusion, I wish to express my thanks to Mr. Player for his 

 analysis, and for many valuable suggestions as to the treatment of 

 the rock, and to Prof. Thorpe for his determination of the humic 

 acid. To Dr. Hinde, Mr. Teall, and Mr. Dick also I am indebted 

 tor much assistance in the examination of the chalk under the 

 microscope. 



Note. — A month after this paper had been read, I received a 

 proof of a communication made in Eebruary to the Eoyal Academy of 

 Belgium by MM. Renard and Cornet, and thus learnt for the first time 

 that they had been engaged in an exhaustive microscopic examination 

 of the phosphatic chalks of the Continent *. It was a pleasure to me 

 to find that my observations on these rocks, which were carried only 

 so far as to enable me to institute a comparison between the English 

 and Continental chalks, are in the closest possible accord with those 

 of MM. Eenard and Cornet. The fact that the MS. of my paper 

 had passed out of my hands before the publication of their results 

 accounts for my not having acknowledged in the foregoing pages 

 their priority in many important observations. Among these I may 

 mention the recognition of fish-remains in all the known phosphatic 

 chalks.— (May, 1891.) 



EXPLANATION OF FIGURES. 



(Figs. 2, 3, 4, 5, and 6 by transmitted light.) 



Fig. 1. Coprclites, selected to show the transverse markings attributed to 

 the intestinal folds. One contains a prism from the shell of an 

 Inoceramtis. 



2. Fragment of bone, showing lacunae. 



3. F'ragment of bone, showing lacunai ; from Dr. Hinde's specimens. 



4. Fragment of bone, bored by a fungus or alga. 



5. Fragment of a fish-scale. 



6. Fragment of a fish-scale, bored by a fungus or alga ; from Dr. Hinde's 



specimens. 



(Figs. 2, 3, 4, and 5 were photographed from drawings by the Author.) 



Discussion. 



Dr. G. J. HiNDB said that he had examined microscopically the 

 phosphatic chalk of Taplow, and compared it with the similar 

 material from Doullens and Ciply, and he fully agreed with Mr. 



* ' Reuherches micrographiques sur la nature et I'origine des roches phos- 

 phat^es,' Bull. Acad. Roy. Belgique, S*"* serie, t. xxi. (1891) p. 126. 



