With respect to Falconer's series of Elephants (112/5. In 1837 Dr. Falconer and Sir Proby Cautley collected a large number of fossil remains from the Siwalik Hills. Falconer and Cautley, "Fauna Antiqua Sivalensis," 1845-49.), I think the case could be answered better than I have done in the "Origin," page 334. (112/6. "Origin of Species," Edition I., page 334. "It is no real objection to the truth of the statement that the fauna of each period as a whole is nearly intermediate in character between the preceding and succeeding faunas, that certain genera offer exceptions to the rule. For instance, mastodons and elephants, when arranged by Dr. Falconer in two series, first according to their mutual affinities and then according to their periods of existence, do not accord in arrangement. The species extreme in character are not the oldest, or the most recent; nor are those which are intermediate in character intermediate in age. But supposing for an instant, in this and other such cases, that the record of the first appearance and disappearance of the species was perfect, we have no reason to believe that forms successively produced necessarily endure for corresponding lengths of time. A very ancient form might occasionally last much longer than a form elsewhere subsequently produced, especially in the case of terrestrial productions inhabiting separated districts" (pages 334-5). The same words occur in the later edition of the "Origin" (Edition VI., page 306.) All these new discoveries show how imperfect the discovered series is, which Falconer thought years ago was nearly perfect. I will send to-day or to-morrow two articles by Asa Gray. The longer one (now not finally corrected) will come out in the October "Atlantic Monthly," and they can be got at Trubner's. Hearty thanks for all your kindness. Do not hurry over Asa Gray. He strikes me as one of the best reasoners and writers I ever read. He knows my book as well as I do myself. LETTER 113. TO C. LYELL. 15, Marine Parade, Eastbourne, October 3rd [1860]. Your last letter has interested me much in many ways. I enclose a letter of Wyman's which touches on brains. Wyman is mistaken in supposing that I did not know that the Cave-rat was an American form; I made special enquiries. He does not know that the eye of the Tucotuco was carefully dissected.