150 DR. C. I. FOESYTH MAJOR ON THE [Feb. 19, 



In JSf. australis (PI. XI. fig. 1) we have the ansta posterior lacr. 



less flattened than the crista mit. — dividing the lacrymal into 



an intra-orbital and a shghtly extra-orbital portion. The whole 

 anterior margin of the fossa 1. is formed by the maxilla, to a 

 larger extent than is the case in Propithecus (PI. XI. fig. 4). As 

 the comparison of the figures Avill show, the lacrymal and its 

 fossa are less produced on the face than in the extreme cases of 

 platyrhine and eatarhine monkeys. 



In Nesopithecus roberti (PL XI. fig. 2) the crista anterior is 

 stronger than the crista posterior, of which the antero-inferior 

 portion is much flattened. The fossa and the whole of the lacrymal 

 bone remain within the orbit. The lower pai-t of the crista 

 anterior, which forms the anterior boundary of the fossa, is 

 supported by the maxilla. In the upper part the lacrymo-maxillary 

 suture runs on the crista anterior, both bones consequently 

 partaking in its formation. This is precisely the condition pre- 

 sented by some platyrhine monkeys (e. g. Brachyurus and some 

 species of Nyctijnthecus) and by the majority of the lower Catarhiuse. 



Summary and Conclusions. 



It has been said that in the lower Mammalia the lacrymal 

 belongs to the bones of the face (" Antlitzknochen "), and that in 

 the Sauropsida it is likewise situated mostly on the surface of the 

 cranium \ I am not so sure that what we call lacrymal in the 

 Sauropsida is exactly the homologue of the Mammalian lacrymal ; 

 but apart from that, the great elongation of the facial cranium, 

 where it occurs in the Eeptilia, may or may not be the primitive 

 condition. Leaving therefore aside the Sauropsida, and coming to 

 the Mammalia, it is not a character of Insectivora genei'ally ^ to 

 have their lacrymal for the greater part, and the canalis lacrymalis 

 as well, on the surface of the skull. In the Insectivora with a 

 largely produced facial portion, e. g. Erinaceus and Oentetes, the 

 first stages, if W. K. Parker's ^ figures are to be relied upon, have 

 the canalis inside the orbit. 



As to the Prosimise, if in the future we come upon forms in the 

 Middle or Lower Tertiaries exhibiting a facial expansion of the 

 lacrymal, and a facial fossa 1., it will then be the time to ventilate 

 the question, whether a similar condition might after all be the 

 primitive one in the ProsimisD. Por the present we have to reckon 

 only with the known facts. In Adapts parisiensis we have found 

 the fossa lacrymalis as well as the whole bone to be inside the 

 orbit ; the lacrymal is fairly large. Prom this condition, the 

 form of the lacrymal of recent Lemurs generally can have been 

 arrived at by the development of a crista posterior; that of the non- 

 Malagasy Lemurs, besides, by a gradual reduction of the lacrymal; 



1 G-egenbaur, op. cit. p. 174. - Id. ibid. 



^ W. K. Parker, " On the Structure aud Development of the Skull in the 

 Mammalia, III. Insectivora," Pliil. Trans. E. Soc. 1885, pi. 20. fig. 3, pi. 32. 

 fiff. 3. 



