The present volume is a mere abstract, and there are great omissions.

One main one, which I have rectified in the foreign editions, is an explanation (which has satisfied Lyell, who made the same objection with you) why many forms do not progress or advance (and I quite agree about some retrograding).

I have also a MS.

discussion on beauty; but do you really suppose that for instance Diatomaceae were created beautiful that man, after millions of generations, should admire them through the microscope?
(97/1.

Thwaites (1811-82) published several papers on the Diatomaceae ("On Conjugation in the Diatomaceae," "Ann.