To what has already been said in the Introduction to the first part To f .this memoir I may add that the magnitude of the material was not fully appreciated when that Introduction was written. Dr. Aldinger's large collection consisted essentially of ammonites; and the reader who peruses the present part will see at once that the beauty of the preservation of these ammonites of which I spoke is in striking contrast to the general defectiveness of the Oxfordian and Lower Kimmeridgian invertebrates illustrated in the first part. Compared with the ammonites, the few other mollusca in the collection were so negligible that I did not hesitate to include them in the account, partly because their description by specialists would have meant a long delay. Since February, however, and as the other invertebrates in Mr. Rosenkrantz's collections were gradually being unpacked, there accumulated such a mass of material that in spite of much of it being named by Rosenkrantz, I began to regret having included fossils other than cephalopoda in my account. <...>
