Intelligence and Miscellaneous Articles. 141 



in the development of the present coast of the north side of the 

 English Channel, and to ascertain the sources of the diversified 

 faunas. 



The first traces of marine action on the South Coast in Post- 

 Tertiary times are found on the foreshore in Bracklesham Bay. The 

 author's reading of the section is somewhat different from that of 

 the late Mr. Godwin-Austen; and he divides the marine series into 



(1) an estuarine clay with Mollusca common to estuarine flats ; 



(2) a compact hard mud ; and (3) a bed of fine sandy silt with many 

 organisms. These beds indicate a change from estuarine to deep- 

 water conditions. A full list of the Selsey fossils is given, including, 

 amongst other animals, upwards of 200 Mollusca. Of 35 species of 

 Mollusca not now living in Britain, the majority exist in Lusitanian, 

 Mediterranean, or African waters ; furthermore, nearly 45 per cent 

 of the Mollusca are common to the older Crags of the Eastern 

 counties. The author considers the fauna of the Portland Bill 

 shell-beds to indicate the further opening of the Channel subsequent 

 to the formation of the Severn Straits, and believes that this fauna 

 represents the deposits wanting between the Selsey mud-deposits 

 and the erratic blocks which, according to him, overlie the mud ; 

 these Portland shells indicate an intermediate temperature " rather 

 southern than northern " according to Dr. Gwyn Jeffreys. 



In conclusion, details concerning still newer beds are given, and 

 lists of fossils found therein ; and the author observes that there is 

 no evidence to show when the English Channel finally opened up, 

 beyond the suggestion of Mr. Godwin- Austen that, if the Sangatte 

 beds and the Coombe Rock are of the same period, it must have taken 

 place after their formation. 



XXII. Intelligence and Miscellaneous Articles. 



ON THE ANALYSIS OF THE LIGHT DIFFUSED BY THE SKY. 

 BY A. CROVA. 



IN a preceding communication I gave* the results of my first 

 researches on this subject, explained the method of observation, 

 and discussed the curves obtained ; in this note I resume the dis- 

 cussion of the results to which the method of calculation adopted 

 has led me, and the comparison of the 1890 observations with those 

 made before both in Erance and abroad. 



The formula of Lord Rayleigh, deduced from Stokes's theoryt, 

 is 



. AT a 2 



in which t is the intensity of the light diffracted by a point of the 



* Comptes Rendus, xix. p. 493; Ann. de Chim. et de Phys. ser. 6, xx. 

 p. 480. _ 



t Phil. Mag. ser. 4, xli. p. 107 (1871). 



