This genus contains, according to Dr. Forsyth Major, as many as seven species. This excellent comparative anatomist has made a very careful revision of the group, and the present writer has gratefully to acknowledge from him many valuable notes incorporated under this section, as well as his kindness in supplying for publication the diagnoses of his new species. Dr. Major divides these seven species into two series:--(A) a group of four larger species, and (B) a group of three smaller species. The members of this genus are smaller than the True Lemurs of the genus _Lemur_. Their head is conical and short, their ears large, round, and membranaceous, and the tail is shorter than the body. In this latter character and in their shorter limbs they differ from _Mixocebus_. The fourth finger and toe are the longest digits of their respective extremities, the nails of all are keeled, and that of the great toe is very large and flat. {84}In the skull, the muzzle is longer than the longitudinal diameter of its orbit in the series of larger species (Section A); in the smaller species (Section B) the muzzle is shorter. Their dentition presents several important characters. The series of upper molars and pre-molars form almost a straight line, both sides being almost parallel, or only slightly convergent towards the front. In the upper jaw the incisors are wanting; the canines are very large and grooved internally, and have a posterior heel. There is no gap between them and the anterior pre-molar, which last is vertically taller than the rest, and has one cusp to the outside, whereas the median and posterior have an inner cusp as well. The anterior and median molars have the inner hind cusp rudimentary, but the cingulum rises into a minute cusp, both at the fore and hind edge; the posterior molar is three-cusped. The whole of the cheek-teeth gradually broaden and decrease in vertical height from before backward as far as the median molar. In the lower jaw the anterior pre-molars are large, canine-like, and decumbent, and have a strong process on their anterior margin (resembling that in the corresponding tooth in _Indris_); the median and posterior pre-molars have one external cusp, and the latter tooth one interior cusp in addition. The anterior and median molars have a rudimentary fifth cusp, which is large in the posterior molar.