444 STYLOCTESIUM. 



smoothly rounded ; no trace of posterior and anterior basal ledges. 

 m- rteropine, equal in ai/e to p, ; m^ eutirel}' wantiiiis;. 



External clutractcrs. — Wings Irom sides of back and base of second 

 toe; wing-indices not differing appreciably from those of Fterojn'n, 

 JS'o tail. Inter femoral scarcely des'eloped in centre. Calcar short, 

 about one-sixth (in Ftcrojixs generally about one-third, rarely only 

 one-fourth) of total lengtli of foot with claws. 



Affinities. — Sti/locieniuDi is a rather slightly specialized offslioot 

 of that branch of Pteroims which, in another direction, has developed 

 into the species of the Pieropus temmincki and lomhocensis groups. 

 In nearly all important dental, cranial, and external characters it 

 is either closely approached by, or perfectly similar to, tb.e living 

 reitrcsentatives of those groups : — (1) In Ft. loinhocemis the canines 

 are short and thick, and the middle pair of lower incisors (i,) so 

 much reduced as to be nearly rudimentary ; in Styhctenium the 

 canines are still thicker, and i, has entirely disappeared : (2) in 

 I't. lomhocensis m^ is conspicuously reduced, almost rudimentary, in 

 Sfi/loctenium it has disappeared : (3) in general shape and nearly 

 all details the skull of Styloctenium is closely similar to tliat of 

 Ft. lomhorensis and tcmmincH (compare fig. 23 with fig. 13, p. 27<*, 

 skull of Ft. solitarius); the mandible is weaker than in the heavy- 

 toothed Ft. lomhocensis, but in every respect similar to that of 

 Ft. cajjistratus : (4) the ears of Slylodeaium arc similar in shape 

 and size to those of Ft. lomboc«nsis and temmincki : (5) the 

 quality of the fur (soft and silky) quite as in the specn's of 

 the Ft. temviincJi-i group; distribution of fur, even to the smallest 

 details (hairing of forearm, tibia, and metatarsus) as in Ft. pcr- 

 sonatas: (6) one of the most conspicuous external features of the 

 three species of the Ft. ieinminchi group is the unusually light 

 (silvery greyish or silvery huffy) colour of the fur, which on 

 spreading shows sharply contrasting seal-brown bases to the hairs ; 

 ]irecisely the same colour characters are found in iSfi/locfcnium : 

 (7) Ft. persoiKitKS and capistrata.s are unique in the genus Ftcroi>uf< 

 in having the head marked with sharply defined white and seal- 

 brown stripes and spots ; the same peculiar pattern is fouud in 

 IStyloctenium (the seal-brown colour lightened to cinnamon) to such 

 extent that the white stripes and spots arc exactly similar in 

 position to those oi Ft. 2^ersomiivs (white median stripe on muzzle, 

 white supraocular spot, white spot at angle of mouth extending 

 forward along upper and lower lips): (S) the calcar is somewhat 

 shorter than usual in the Ft. temmincki gvoM]), in Stylocteniwn more 

 conspicuously shortened. In size the single species of Styloctenium 

 is similar to Ft.jjersonatKS.- — The slender terete shape of the incisors 

 of Styloctenium is in all probability a secondary character ; it re- 

 occurs in Aceroclon. To the circular or oval form of the niolariform 

 teeth, with broadened and smoothly rounded cusps and ridges, there 

 are more or less close parallels in different species of Fierojms 

 (Ft. puiiuanus, neohibcrnicuti, macrotis, cpidanus). 



