136 



DE. C. I. FOBSYTH MAJOB ON THE 



[Feb. 19, 



posterior, the lacrymal fossa comes to be extra-orbital. Eecent 

 Lemuridte show a considerable amount of variation in this respect, 

 and we have therefore to examine them somewhat in detail. 



Perodicticus. 



Here we meet with a crista posterior, separating a pars facialis 

 and a pars orbitalis ; the whole of the former's fossa is bordered 

 by the maxilla. In none of the species does tlie malar reach the 

 lacrymal. 



In the specimen which is the type of Bennett's " P. geoffroyi " 

 (Br.M.Z. D.No. 55.12.26.230) (see text-fig. 33), the pars facialis 

 has a very limited extent ; the piars orbitalis starts from the crista 

 posterior in a lateral and downward direction, till it reaches an 

 unossified opening, a sort of irregularly-shaped fontanelle ; in 

 front it unites by a suture with the maxillary, behind with the os 

 planum. On the medial side of the crista posterior, situated 

 between the lacrymal, frontal and maxilla, is an intercalar bone (x). 



In the P. potto (Br. M. Z. D. Nos. 56.11.10.5 and 46.12.5.1) 

 (text-fig. 31) the orbital portion of the lacrymal is of moderate 

 size, and delimited posteriorly- — proceeding from the medial 

 towards the lateral side — by the frontal, os planum, maxillary, 

 lacuna, maxillary. On the orbital margin the lacrymal is I'aised to 

 a crista posterior, and unites with the frontal and maxillary, which 

 form the medial and lateral continuation, respecti\ ely, of the crista 

 posterior. The lateral and anterior margins of the facial fossa I. 

 are formed by the maxillary. In older specimens of the Potto the 

 sutures are obliterated. 



Text-fig. 31. 



Text-fig. 32. 



Text-fig. 33. 



Text-fig. 31. Orbital region oi Perodicticus -potto (Br. M. No. 46.12.5.1), about 



nut. size. 

 Text-fig. 32. The same of Perodiclicus calabarensis (Br. M. No. 46.ll.lU.5j, 



about nat. size. 

 Text-fig. 33. The same of the type of "Perodicticus geoffroi/i Benn.'" (Br. M. 



No. 55.12.26.230)," about | nat. size. 



(Lettering as iu text-fig. 26.) 



In Perodicticus calabarensis (Br. M. Z. D. No. 0.11.30.1 ; $ ) 

 the orbital part of the lacrymal is very narrow (transversely), and 

 so is the pars facialis, which is, however, more elongate than in 



