The late Director of the British Museum, Dr. J. E. Gray in establishing this species, (Catalogue of Monkeys, London, 1 Dec. 1870, p. 133) assigns to it the following characteristics: “Back iron-grey, with a rufous tinge; the hairs black, with a subapical rufous band, and the lower part leadcoloured; throat whitish; patch on rump at base of tail yellowish. — Hapalemur griseus, Schlegel et Pollen, Faune Madagasc. p. 6, t. 3 et 7, fig. 4. (skull without upper cutting-teeth) — Habits Madagascar. — This may be Hapalemur olivacea; but that species is very imperfectly described, and it is said to have a different form of the hinder part of the lower jaw; but what the difference is, is not mentioned; and I do not see any difference in the hinder part of the lower jaws of the two species. The front of the jaw in H. griseus is very much more slender and weak than in H. simus. The colour of the fur is exactly similar to that of H. griseus; only there is a pale spot on the rump at the base of the tail, which may be accidental, or caused by the manner in which it was confined in its cage.” Other observations by the same author on this subject are contained in the Proceedings of the Zoological Society, London 1870, p. 828. We think is necessary to repeat these also: “Notes on Hapalemur simus, a new species living in the Gardens of the Society. By Dr. J. E. Gray, F. R. S. etc.