I did not know that anyone in Germany had noticed them until I received the copy of your "Bericht" for 1856, which you were kind enough to send me. I owe you many thanks for the manner in which you speak of them, and I assure you it was a source of great pleasure and encouragement to me to find so competent a judge as yourself appreciating and sympathising with my objects. Particular branches of zoology have been cultivated in this country with great success, as you are well aware, but ten years ago I do not believe that there were half a dozen of my countrymen who had the slightest comprehension of morphology, and of what you and I should call "Wissenschaftliche Zoologie." Those who thought about the matter at all took Owen's osteological extravaganzas for the ne plus ultra of morphological speculation. I learned the meaning of Morphology and the value of development as the criterion of morphological views--first, from the study of the Hydrozoa during a long voyage, and secondly, from the writings of Von Baer. I have done my best, both by precept and practice, to inaugurate better methods and a better spirit than had long prevailed. Others have taken the same views, and I confidently hope that a new epoch for zoology is dawning among us. I do not claim for myself any great share in the good work, but I have not flinched when there was anything to be done. Under these circumstances you will imagine that it was very pleasant to find on your side a recognition of what I was about. I sent you, through the booksellers, some time ago a copy of my memoir on Aphis. I find from Moleschott's "Untersuchungen" that you must have been working at this subject contemporaneously with myself, and it was very satisfactory to find so close a concordance in essentials between our results. Your memoirs are extremely interesting, and to some extent anticipated results at which my friend, Mr. Lubbock [The present Sir John Lubbock, M.P.] (a very competent worker, with whose paper on Daphnia you are doubtless acquainted), had arrived. I should be very glad to know what you think of my views of the composition of the articulate head. I have been greatly interested also in your Memoir on Pentastomum. There can be no difficulty about getting a notice of it in our journals, and, indeed, I will see to it myself. Pray do me the favour to let me know whenever I can serve you in this or other ways. I shall do myself the pleasure of forwarding to you immediately, through the booksellers, a lecture of mine on the Theory of the Vertebrate Skull, which is just published, and also a little paper on the development of the tail in fishes. I am sorry to say that I have but little time for working at these matters now, as my position at the School of Mines obliges me to confine myself more and more to Paleontology. However, I keep to the anatomical side of that sort of work, and so, now and then, I hope to emerge from amidst the fossils with a bit of recent anatomy.