Dr Knox on the Structure of' the Gibbons. 155 



ter. Indeed, the advantages of employing sapphire magnifiers is^ 

 so well established by experience, that nothing is now wanted as 

 a medium between the diamond and glass. 



May 1829. A. P. 



Art. XXIII. — Remarks on the structure of the Gibbons, a 

 subgenus of the Orangs or Pitheci. By Dr K^!ox, Lec- 

 turer on Anatomy. Communicated by the Author. 



Two specimens of Gibbons, apparently the species or variety 

 (for there is great confusion in all these matters as regards 

 the higher order of the Quadrumana,) called by naturalists 

 Pithecus leuciscuSf were put into my hands by J. Robison 

 Esq. Secretary to the Royal Society, (to which they were 

 sent by George Swinton, Esq.) with a request to prepare 

 them in whatever way I thought most beneficial to science. 

 They came originally from Assam, and having been long pre- 

 served in spirits, it was not easy to determine very precisely 

 the colour of the head and other external marks, in which the 

 naturalist is of course much interested ; but they, were Orangs 

 of the subgenus Gibbon, and corresponded tolerably well to 

 the Pithecus leuciscus of Schreber and Geoffroy ; but known 

 also by a variety of other denominations, such as, Orang, Wou 

 Wou, Simia lar. Gibbon cendre, &c. They were stated to be 

 " mother and son,'' but they proved both females, the one 

 seemingly perfectly adult ; the other quite young. The 

 youngest was much the darker, so that had they not arrived 

 together, and been designated as young and old of the same 

 species, they might well have passed for different species ; and 

 indeed, when I describe these specimens as belonging to the 

 species called leuciscus, I do not pretend but what they may 

 really be after all the proper Orang Gibbon, the Simia lar and 

 hngimana of Linne and Schreber. The description given of 

 these Gibbons by naturalists, seems to me extremely imper- 

 fect, and not warranting their division into species. The Simia 

 hngimana of Desmarest was described from a single specimen 

 dissected ( .? ) by Daubenton, which obviously must have 

 been quite young, since it weighed only nine pounds. The 

 Pithecus variegatus of the same excellent naturalist (Des- 



