ORBITOTEMPORAL REGION OF SKULL OF LEMUR. 329 



that the determining of sutures separating different bony elements 

 becomes a hopeless task. 



More than this, synostosis of the different elements is effected 

 at a comparatively early stage in the Lemurs. 



Text- figure 5. 



Orbit of an adult $ L. catta. Lettering as in text-figs. 3 & 4. 



The palate-bone is not indicated by lettering and is apparently subdivided into 

 two portions by the inflation of its anterior extremity. 



Before the comparison of different species, or the much more 

 important contrasting of the Malagasy and non-Malagasy forms, 

 can be undertaken, an examination must be made of foetal and 

 young stages, and until that is done the question of the variability 

 of this region must remain an open one. But, for the genus 

 Lemur, the two foetal examples described here appear to indicate 

 clearly that the os planum of the ethmoid is lacking from the 

 orbital wall, and that a very common mammalian, but definitely 

 non -primate, arrangement of the bony elements is present in this 

 region. 



Proc. Zool. Soc— 1917, No. XXIII, 



23 



