“Next in importance I would place the Tapirs. This is one of a family whose geological antecedents are very important and interesting. The Mastodons, the Palæotherium, the Dinotherium, and other large Mammalia of the Tertiaries, are closely related to the Tapir. The elephant, rhinoceros, and the like, are of the same family. From its structural standing next to the elephant, which is placed highest in the group, the embryology of the Tapir would give us a very complete series of changes. It would seem from some of the fossil remains of this family that the Pachyderms were formerly more nearly related to the Ruminants and Rodents than they now are. Therefore it would be well to study the embryology of the Capivari, the Paca, and the Peccary, in connection with that of the Tapir. Lastly, it will be important to learn something of the embryology of the Manatee or Sea-Cow of the Amazons. It is something like a porpoise in outline, and seems to be the modern representative of the ancient Dinotherium.” _April 12th._—The lecture to-day was addressed especially to the ornithologists of the party, its object being to show how the same method of study,—that of testing the classification by the phases of growth in the different groups,—might be applied to the birds as profitably as to other types. We have made good progress in the last forty-eight hours, and are fast leaving our friends “the trades” behind. The captain promises us smooth waters in a day or two. With the dying away of the wind will come greater heat, but as yet we have had no intensely warm weather. The sun, however, keeps us within doors a great part of the day, but in the evening we sit on the guards, watch the sunset over the waters, and then the moonlight, and so while away the time till nine or ten o’clock, when one by one the party disperses. The sea has been so rough that we have not been able to capture anything, but when we get into smoother waters, our naturalists will be on the look out for jelly-fish, argonautas, and the like. _April 13th._—In to-day’s lecture Mr. Agassiz returned again to the subject of geographical distribution and the importance of localizing the collections with great precision.