of the Rliiiioloplius arcuatus Group. 287 



Wing-indices. 



General Remarks on the Gr 



oup. 



All the species known of the Rh, arcuatus group are 

 so far developed as to have the median anterior nasal 

 swellings more abruptly projecting than usual in the 

 genus, the middle lower premolar {p^) situated external to 

 the tooth-row or quite obliterated, the fifth metacarpal 

 slightly longer than the fourth, and the second phalau.t of 

 the third finger lengthened. All these are secondary 

 characters. We lack the direct information as to the 

 affinities of the group, which could have been derived from 

 species on a more primitive level of development. Never- 

 theless, there can scarcely be any doubt that the arcuatus 

 group is more closely related to Rh. philippinensis and 

 Rh. macrotis than to any other now existing types of the 

 genus. The strong development of the nose-leaves, the size 

 of the internasal lobes, the shape of the connecting-process 

 and the lancet, the broad ears, are characters which seem to 

 point in that direction. 



Rh. arcuatus is unquestionably the most primitive species 

 of the group, as proved by the slightly less projecting nasal 

 swellings, the small teeth, the narrow temporal fossa, the 

 very low sagittal crest, the normal shape of the horseshoe, 

 the somewhat less pronounced " ovate '^ shape of the sella. 

 Of the two local forms here discriminated the southern 

 {Rh. e. exiguus) is a little higher developed in dentition : 

 JO3 is very often lost ; the narrow horseshoe is probably a 

 secondary character. 



Rh. subrufus is a modification of the arcuatus type : more 



