. . .These last months have been a time of trial to me, and I have been forced to give up my correspondence completely in order to meet the ever-increasing demands of my work. You know how difficult it is to find a quiet moment and an easy mind for writing, when one is pursued by printing or lithographic proofs, and forced besides to prepare unceasing occupation for numerous employees. Add to this the close research required by the work of editing, and you surely will find an excuse for my delay. I think I have already written you that in order to have everything under my own eye, I had founded a lithographic establishment at Neuchatel in the hope of avoiding in future the procrastinations to which my proofs were liable when the work was done at Munich. . .I hope that my new publications will be sufficiently well received to justify me in supporting an establishment unique of its kind, which I have founded solely in the interest of science and at the risk of my peace and my health. If I give you all these details, it is simply to explain my silence, which was caused not by pure negligence, but by the demands of an undertaking in the success of which my very existence is involved. . .This week I shall forward to the Secretary of the British Association for the Advancement of Science all that I have been able to do thus far, being unable to bring it myself, as I had hoped. You would oblige me greatly if you would give a look at these different works, which may, I hope, have various claims on your interest. First, there is the tenth number of the "Fossil Fishes," though the whole supply of publisher's copies will only be sent a few weeks later. Then there are the seven first plates of my sea-urchins, engraved with much care and with many details. A third series of plates relates to critical studies on fossil mollusks, little or erroneously known, and on their internal casts. This is a quite novel side of the study of shells, and will throw light on the organization of animals known hitherto only by the shell. I have made a plaster collection of them for the Geological Society. They have been packed some time, but my late journey to Paris has prevented me from forwarding them till now. As soon as I have a moment, I shall make out the catalogue and send it on. When you go to London, do not fail to examine them; the result is curious enough. Finally, the plates for the first number of my "Fresh-Water Fishes" are in great part finished, and also included in my package for Newcastle. . .The plates are executed by a new process, and printed in various tints on different stones, resulting in a remarkable uniformity of coloring in all the impressions. . .