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Show 132 DR. C. I. FORSYTH MAJOR ON THE [Feb. 19, figures. Of Monkeys I have only added those of Callithrix (text-fig. 46, p. 142) and Chrysothrix (text-fig. 29, below). It has been stated that the bone is missing in the latter genus1; as may be seen from the figure, it is a large bone, and as such has been mentioned already by Kostlin 2. Text-fig. 27. IVxt-fig. 28. Text-fig. 20. Text-fig. 27. Orbital region of Avahis laniger, young, nat. size. Text-fig. 28. The same of Propitkecus coquereli (Br. M . No. 91.1.22.1), about § nat. size. Text-fig. 29. The same of Chrysothrix sciureus (Br. M . No. 932 c), about nat. size. (Lettering as in text-fig. 26.) II. T H E LACRYMAL BONE. As one of the distinguishing features between Lemurs and Monkeys is considered the position of the lacrymal fossa, viz., on the facial part of the skull in Lemurs, inside the orbit in Monkeys and Man. The only writer, to my knowledge, who has considered this condition more closely is Gegenbaur3; a summary of his views is given in the following. In lower Mammals the lacrymal is one of the facial bones ; in the Sauropsidae particularly it is for the larger part situated on the surface of the skull. In Lemurs it has preserved this position in such a manner that not even the canalis lacrymalis begins within the orbit. The same remark applies to Insectivora aud Chiroptera. In Monkeys, the bone has been stated by older anatomists (Kostlin, Stannius) to occupy the same position as in Mail, having retreated within the orbit. Gegenbaur, however, points out that considerable variations occur amongst Monkeys. Of Platyrliime, three genera are taken in consideration : Ateles, Mycetes, and Nyctipithecus, In the former two "the lacrymal 1 " Chez les Baimiris, qui, seuls dans tout l'ordre des Primates, n'ont pas d'os planum, la place ne reste vide que par suite d'un defaut d'ossification." Alfr. Grandidier, Hist, phys., naturelle et politique de Madagascar ; vol. vi. Hist. Nat. des Mammiferes, par M M . Alph. Milne-Edwards et Alfr. Grandidier, Tome I.-Teste i. p. 16, footnote (1875). 2 Op. cit. pp. 92, 93. 3 G. Gegenbaur, " Ueber die Pars facialis des Lacrymale des Menschen,'' Morph. Jahrb. vii. ?y. 173-176 (1882). |
