2. _Georgetown, District of Columbia._—In 1835 (Med. and Phys. Researches, p. 267), Dr. Richard Harlan acknowledged the receipt, at the Academy of Natural Sciences of Philadelphia, of remains of a fossil horse found at Georgetown in constructing the canal along the Potomac. These were probably teeth and had been sent by Colonel I. J. Abert, of Washington. They ought now to be in the Academy mentioned. In 1850, R. W. Gibbes (Proc. Amer. Assoc. Adv. Sci., vol. III, p. 67) presented before the American Association of Sciences a specimen (a tooth?) which he said came from the bank of the Potomac and was associated with a tooth of _Bos_ (_Bison_). How he came to have this was not related, nor is it certain that it was found near Washington. 3. _Mitchellville, Prince George’s County._—In the U. S. National Museum are 2 upper teeth, molars or premolars (No. 8813), of a horse found on his estate northwest from the town named, by Mr. Edward S. Walker. They were presented to the National Museum by Dr. Edward W. Berry, of John Hopkins University. These teeth, apparently first and second molars, seem to belong to an undescribed species. The table gives the height of the teeth and dimensions of the grinding-surface in millimeters. ┌────────────┬────────────┬────────────┬────────────┬────────────┐ │ Tooth. │ Height. │ Length. │ Width. │ Protocone. │ ├────────────┼────────────┼────────────┼────────────┼────────────┤ │M^1 │70 │29.5 │25 │12 │ │M^2 │73 │30 │23 │14.5 │ └────────────┴────────────┴────────────┴────────────┴────────────┘ The teeth present the appearance of having been little worn. Measurements of the crown taken about one-third the distance to the base are as follows: ┌────────────────┬────────────────┬────────────────┬────────────────┐ │ Tooth. │ Length. │ Width. │ Protocone. │ ├────────────────┼────────────────┼────────────────┼────────────────┤ │M^1 │25 │25 │11 │ │M^2 │26 │25.2 │13 │ └────────────────┴────────────────┴────────────────┴────────────────┘ The teeth are moderately curved, so that the outer face is convex, the inner concave. Some of the cement is retained and is colored blue with vivianite. The enamel presents less complication than is usually found in either _Equus complicatus_ or _E. leidyi_. The dimensions of the teeth and the narrowness, especially of the second molar, seem to exclude reference to either of the species mentioned.