CORRESPONDENCE. 



257 



siders him to be an advanced geuetheonom of some extinct ape, even 

 should the remains of species be found hereafter more human-like 

 and more manipulative than the gorilla or chimpanzee. 



I am disposed to regard, then, progressive change as one of the 

 great primary modifying principles of organic nature ; and " natural 

 selection" as a secondary one, — the latter subordinately operating 

 in the production oi 'proximately allied specific and varietal forms. 



Some years ago I contributed a few facts, which showed that varia- 

 tions of physical conditions, as depth of water and nature of sea- 

 bottom, induced in certain British shells modifications of form equal 

 to differences prevailing between many species of mollusca;* in a 

 paper published a year or two previously, I particularly noticed the 

 remarkable, and, in many cases, imperceptible gradations of generic 

 characters running through the tetrabranchiate Cephalopods ;f and 

 in my "Monograph," I have pointed out the various forms assumed 

 by Camaroplioria ScMotheimi, and some other Permian fossils. These 

 may be taken as evidences that I have not been inattentive to the 

 vexed question of species. Of course, it would ill become any one 

 to dogmatize on such a subject, and disbelieve in the future turning- 

 up of facts subversive of his preconceived notions ; nevertheless, I 

 feel myself bound to declare, that all my observations and reasoning 

 incline me to believe in the two modes of creation as herein ad- 

 vanced. 



COEEESPONDENCE. 



Professor King's Etratigrapliical Tables. 



Sir, — The Table of British Eocks, by Professor King, given in the last 

 number of the ' Geologist ' (pp. 193-7), I cannot let pass without saying, 

 that however perfect it may be as regards those Irish rocks amongst 

 which the Professor teaches, it is not as useful as might be to a student 

 in the South-east of England. 



Its many imperfections will be seen on comparing it with the table 

 given in Lyell's ' Elements,' with those of a more detailed kind scattered 

 through the lately-published edition of Jukes's ' Manual,' or with the 

 Index of Colours of the Geological Survey. The following are amongst 

 the most striking mistakes (in the Lower Tertiary and the Secondary 

 rocks) : — 



1. The Upper and Lower BagsJiot Beds are not noticed, only the Middle 

 Bagshot (Barton and Bracklesham) being given. The Woolwich and 

 Reading Beds are also left out, although the Thanet Sand (of less impor- 

 tance) is given. 



2. The Loiver Greensand, save its lowest bed (the somewhat local 

 Atherfield Clay), has escaped notice. 



3. The Kimmeridge Clay, the Coral Bag (with its associated bed.< 



* See Annals and Magazine of Natural History, vols, xviii. and xix. 

 t See ibid., vol. xiv. 

 VOL. Y. 2 L 



