■24 MR. R. I. POCOCK ON THE EXTERNAL 



in Arctocehus. Huxley cites the presence of this fold as one of 

 the features distinguishing this genus from Perodicticus. 



Although the ear of CMromys is relatively as large as in the 

 Galagos, it is not ribbed and grooved above the capsxde. The 

 supratragus is a thickened i-idge as in Lemur ; but the tragus is 

 not an angular projection as in that genus but a simple ridge, 

 and the notch between it and the well-developed antitragus is 

 comparatively deep and wide. Its lower rim, however, does not 

 extend downwards so low as the external auditoiy meatus, the 

 portion of the pinna just beyond this meatus being elevated as in 

 Carnivora, Ruminants, and many other Mammals. 



The ear of Tarsius is similar in all essential details to that of 

 the Galagos, except that the supratragus aiid the antitragus are 

 somewhat larger and more valvular (text-fig. 2, A). 



The simplest type of ear in this group, a,nd I suspect the most 

 primitive, is that of Lemur and Chirogcdeits, ears with a greatly 

 expanded and ribbed pinna and valvular supratragus being 

 derivative and specialised structures. According to this view the 

 ear of Tarsms is the least primitive of all. It is gradationally 

 linked with the ear of Chirogcdeus by the ears of Galago and 

 MicrocebiLs. 



The Faded and Carpal Vibrissa}. 



In the development of the facial vibrissfe * the most generalised 

 type I have examined is Chirogaleus major, where the mystacial, 

 superciliary, genal, and interramal tufts are all well developed 

 (text-fig. 2, C). There is a single genal tuft on eadi side set low 

 down behind the corner of the mouth. Most of the species 

 referred to Lemur resemble Chirogaleus except that the inter- 

 ramal tuft is absent ; but in L. variegattts it is usually, if not 

 always, retained, although of small size. The full complement of 

 tufts is present in Chiromys, but the vibrissas composing them 

 are generally shorter than in the typical Lemurs, and in two 

 cases the interramal tuft was reduced to a single vibrissa. 



In the Galagos {Galago crassicaudatus, G. senegalensis, and 

 Eemigalago demidojfi) the vibrissee are poorly developed as com- 

 pared with those of the typical Mascarene Lemurs, more par- 

 ticularly Chirogaleus major, with which the Galagos were at one 

 time associated. The intei-ramal tuft appears to be invariably 

 absent, and the genal tuft is set high iip on the cheek a little 

 below and behind the posterior angle of the eye (text-fig. 2, B). 

 It resembles in position the upper genal tuft of the typical 

 Carnivora, whei-eas in Chirogaleics and Lemur the genal tuft 

 resembles in position the lower of the two tufts in that order. 

 In Nycticehus and Perodicticios the vibrissas are even less well 

 developed than in the Galagos, the genal tuft being suppressed 

 in the specimens examined (text-fig. 2, D). The genal and 

 intei'ramal tufts are also absent apparently in Tarsius, although 



* P. Z. S. 1914, pp. 889-912. 



