414 MAN OF SCIENCE. 



you also will be of this opinion when you have thrown 

 your eye over my last publication in the May number 

 of the Quarterly Journal of the Geological Society. I 

 will send you a copy of this Memoir as well as of my last 

 words on Sweden, and also on the Silurian rocks in 

 Cornwall, if you will tell me to what London bookseller 

 I may address them ;* and I beg to call your special 

 attention to my conclusions on the paper on the Silurian 

 Rocks of Sweden. Pray read them first, and then my 

 reply to Sedgwick's new proposal. I have letters from 

 Russia, Scandinavia, Germany, France, and America, 

 all declaratory of firm adhesion to the Silurian faith. 



' Alas ! for one of my generalizations founded on 

 negative evidence (of a very extensive kind, however) on 

 which you built. The Lower Silurian is no longer to 

 be viewed as an invertebrate period ; for the Onchus f 

 (species not yet decided) has been fixed in Llandeilo 

 Flags, and in the Lower Silurian Rocks of Bala. In one 

 respect I am comforted by the discovery, for the form is 

 so very like that of the Onchus Murchisoni of the 

 Ludlow Rocks, that it is clear the Silurian system is 

 one great Natural History series, as proved indeed by 

 all its other organic remains. Professor E. Forbes and 

 every palaeontologist is of this opinion, although the 

 system is divided into upper and lower groups. It 

 must be stated that ichthyolites are most rare, and very 

 peculiar in these protozoic rocks. 



'P.S. I should like you to have seen the Cornish 

 ichthyolites, which are unlike anything known in the 



* ' I will send them to your London publisher in Paternoster Row 

 whose name is on your title-page.' 



f This so-called discovery misled both Sir Roderick and Hugh 

 Miller for the time. It led to the subsequent intention of cancelling 

 one of the chapters in ' Footprints of the Creator.' 



