COEEESPONDENCE. 
257 
siders him to be an advanced genetheonom 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 pliysical 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 Camarophoria Sclilotlieimi, and some other Perm.ian 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. 
CORRESPONDENCE. 
Professor King^s StratigrapMcal 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 G-eological Survey. The following are amongst 
the most striking mistakes (in the Lower Tertiary and the Secondary 
rocks) : — 
1. The Upper and Lower Bag shot Beds are not noticed, only the Middle 
Bagshot (Barton and Bracklesham) being given. The Woolioich and 
Reading Beds are also left out, although the Thanet Sand (of less impor- 
tance) is given. 
2. The LoLoer Greensand, save its lowest bed (the somewhat local 
Atherfield Clay), has escaped notice. 
3. The Kimmeridge Clay, the Coral Rag (with its associated beds 
* See Annals and Magazine of Natural History, vols, xviii. and xix. 
t See ibid., vol. xiv. 
VOL. V. 2 L 
