384 Correspondence — Rev. A. Irving — Mr. R. Lydekker. 



The author's object in this paper is to trace the successive stages 

 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) abed 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 Jefi'reys. 



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 Eock are of the same ^period, it must have 

 taken place after their formation. -^^ 



coiaiaEsi^oiTiDDs isTCE. 



PFAFF'S "ALLGEMEINE GEOLOGIE." 



Sib, — By an inadvertence I have, in quoting Dr. Pfaff's work on 



p. 301 of the July Number of the Geol. Mag. confused the title 



with that of a well-known work by Justus Eoth. The true title of 



Pfaff's work referred to is Allgemeine Geologie als exacte Wissen- 



schaft. I shall be greatly obliged if you can afford space for this 



correction in the forthcomina; Number. . ^ 



° A, Irving. 



MOLAES OF PERISSODACTTLA ;— A CORRECTION. 



Sir, — In my notice on this subject on page 321, line 15 from top, 

 I have inadvertently written crotchet instead of anti- crotchet. 



E. Lydekker. 



