{109} The absence of intermediate forms between living organisms (and also as regards fossils) is discussed in the _Origin_, Ed. i. pp. 279, 280, vi. p. 413. In the above discussion there is no evidence that the author felt this difficulty so strongly as it is expressed in the _Origin_, Ed. i. p. 299,--as perhaps "the most obvious and gravest objection that can be urged against my theory." But in a rough summary written on the back of the penultimate page of the MS. he refers to the geological evidence:--"Evidence, as far as it does go, is favourable, exceedingly incomplete,--greatest difficulty on this theory. I am convinced not insuperable." Buckland's remarks are given in the _Origin_, Ed. i. p. 329, vi. p. 471. {110} That the evidence of geology, as far as it goes, is favourable to the theory of descent is claimed in the _Origin_, Ed. i. pp. 343-345, vi. pp. 490-492. For the reference to _net_ in the following sentence, see Note 1, p. 48, {Note 161} of this Essay. Referring only to marine animals, which are obviously most likely to be preserved, they must live where <?> sediment (of a kind favourable for preservation, not sand and pebble){111} is depositing quickly and over large area and must be thickly capped, <illegible> littoral deposits: for otherwise denudation <will destroy them>,--they must live in a shallow space which sediment will tend to fill up,--as movement is <in?> progress if soon brought <?> up <?> subject to denudation,--[if] as during subsidence favourable, accords with facts of European deposits{112}, but subsidence apt to destroy agents which produce sediment{113}. {111} See _Origin_, Ed. i. p. 288, vi. p. 422. "The remains that do become embedded, if in sand and gravel, will, when the beds are upraised, generally be dissolved by the percolation of rain-water." {112} The position of the following is not clear:--"Think of immense differences in nature of European deposits,--without interposing new causes,--think of time required by present slow changes, to cause, on very same area, such diverse deposits, iron-sand, chalk, sand, coral, clay!" {113} The paragraph which ends here is difficult to interpret. In spite of obscurity it is easy to recognize the general resemblance to the discussion on the importance of subsidence given in the _Origin_, Ed. i. pp. 290 et seq., vi. pp. 422 et seq.