1901.] SKULLS OF LEMURS ANB MONKEYS. LSS 



The posterior portion of the lacrymal descends to a considerable 

 extent into the orbit, forming a very open angle with the anterior 

 portion — the honiologue of the sulcus lacrymalis — which rims 

 forward almost horizontally. But there is no crest {crista posterior I.) 

 dividing the two portions-^ and the blunt crista anterior is ex- 

 clusively formed by the maxilla, which delimits the laeiymal 

 fossa in front, and at the same time forms the lower anterior 

 margin of the orbit. The lacrymal fossa, therefore, is situated 

 entirely inside the orbit. The malar bone, which laterally con- 

 tinues the lower orbital margin, proceeds farther medially than 

 in Man and generally in Monkeys, without, however, reaching 

 the lacrymal, from which it is separated by a process of the 

 maxillary projecting laterally into the fossa. Medially, a similar 

 process of the frontal enters also the fossa from behind, the 

 lacrymal (the anterior part of which is brokeii in the specimen) 

 being thus situated between the two processes. 



P. Gervais, to whom we owe one of the earliest descriptions of 

 the skull of Adapis parisiensis (" Palceolemur ") \ mentions as 

 one of the Lemurine features of the skull " la position iufero- 

 externe du trou lacrymal et son developpement." In his figure 3 

 (pi. xvii.) are in fact represented two foramina situated on the 

 facial part of the cranium and occupying approximately the 

 position of the fossa lacrymalis in many recent Lemurs. The 

 comparison of Gervais's figure with the skull in the British Museum 

 (No. M 1345) shows, however, that these supposed lacrymal 

 foramina are not foramina at all, but deep circumscribed depressions 

 of the maxillary, in front of crista anterior, which exhibit the 

 appearance of foramina when the shade falls into the hollow. 

 In a subsequent publication by Gervais'^, either the author or 

 the artist seems to have become aware of this fact, for the two ■ 

 supposed foramina are entirely omitted from the figure represent- 

 ing the very same cranium ; the description is, however, reprinted '^ 

 without alteration from the ' Journal.' 



The skulls of Adapis magnus in the Geological Department 

 show the cranial region which interests us here, in a broken 

 condition, and in the same case are unfortunately the skulls 

 of Microchcerus {Necrolemur). Por the present, therefore, the 

 oldest Lemurid exhibiting the lacrymal region shows it to be 

 conformed exactly the inverse of what might haAC been anticipated 

 and in fact has been supposed to be the case. 



Since Adapis parisiensis agrees in several important features 

 with recent, and most of all with the Malagasy, Lemurs ^, it 

 may be fairly taken to be in their ancestral line. The condition 

 of the lacrymal region in recent Lemuridse is easily derivable 

 from that obtaining in A. parisiensis, in supposing that by the flat- 

 tening of the maxilla's crista anterior and the upraising of a crista 



1 Journ. de Zool. ii. p. 422, pi. xvii. (1873). 

 - Zool. et Pal. gen. ii. pi. viii. fig. 2 a (1876). 



3 Op. cit. p. 32. 



4 P. Z. S. 1899, p. 988. 



