538 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxxi. 



f:XPLANATI()N OF PLATE XIII. 



All figures about f natural size. 



Figs. 1-4, Nyct'kebus borneanus, showing progressive increase in size, and the 

 development of the temporal ridges with increasing age. 



1. Adult female, Sanggau, western Borneo. Cat. No. 142238, U.S.N.M. 



2. Adult female, Sanggau, western Borneo. Cat. No. 142239, U.S.N.M. 



3. Old adult male, Tyan, Kapuas River, western Borneo. Cat. No. 142233, U.S.N.M. 



4. Very old adult male, Sakaiam River, Sanggau district, western Borneo. C;at. 

 No. 142234, U.S.N.M., type. 



Figs. 5-8, Nydicebiis midaiaimx, showing progressive increase in size, and the 

 development of the sagittal crest with increasing age. 



5. Nearly adult male, Johore Lama, Malay Peninsula. Cat. No. 114151, U.S.N.M. 



6. Adult female, Rumpin River, Pahang, Malay Peninsula. Cat. No. 115496, 

 U.S.N.M. 



7. Old adult female, Tringauu, :\Ialay Peninsula. Cat. No. 105022, U.S.N.M. 



8. Old adult male, Tapanuli Bay, western Sumatra. Cat. No. 114460, U.S.N.M. 



