70 rrEKOPCTs. 



a bi'oarl, well-defined inner basal ledge iu p,. nip and ni^. this ledga 

 being in reality (quite as in Acerodon) a direct continuation of the 

 posterior ledge along the inner side of the teeth. (_)n close exami- 

 nation a very faint trace of an inner ledge in the lower cheek-teeth 

 is sometimes perceptible in the related Ft. sanwensis and 2^iiosits. 



Traces of antero-internal basal tubercles in p', p', p,, and p^. — In 

 a few species the antero-internal cingulnm of p^ and p'' is somewhat 

 more differentiated than usual, i. e. more distinctly projecting as a 

 narrow ledge : Ft. molossinus and rorh-icensis ; in the latter species 

 the rim of this narrow ledge occasionally develops one or two 

 minute tubercles. Similarly, the antero-internal cingulum of p^, or 

 both p., and p^, shows in certain species a more or less noticeable 

 tendency towards differentiation into a projecting ledge : Pf. nuniai- 

 ensis, samoensls, (t»ctinni(s, insidaris, and phaoccjihaJ us ; at least in 

 J'f. aiieti.anns this ledge develops a minute tubercle. In Ft. psela- 

 jifion the antero-internal portion of j)^ is rather sharply marked off, 

 by a deep groove, from the inner main cusj) of the tooth. — Compare 

 Acej-odon. 



Indications of splitting of ridges of lower molnriform teeth. — In 

 the large majority of species the inner and outer longitudinal ridges 

 (cusps) of all molariform teeth arc perfectly simjilc. On close 

 inspection of p, of Ft. sanioensis and in/osus (allied to Ft. j^selo'phon) 

 a faint transverse dejiression in the inner ridge of that tooth is 

 detectable, at least in some individuals, suggesting an initial stage 

 towards a splitting of tlie ridge into a?) anterior and posterior 

 portion. This leads to Ft. i^selophon, in which the inner ridge of 

 m^ is always slightly but quite distinctly subdivided into an anterior 

 and posterior portion. And finally, in Pt. leiicojitcrns (allied to 

 jiseJaphon) not only the inner but, at least in some individuals, 

 also the outer ridge of m, and m., are similarly subdivided. — 

 Compare Fteralopex. 



m^ and m''.— m.^ is more reduced than usual in the Pt. rayneri 

 group (/'('. cor/iKifuf:, rrn/nen, rHhia)nis, Ifu'eUanits, (jrandis, and 

 chrijsoprocti(s). Eoth m.^ and m" are reduced in the Ft. loinhocensis 

 (Pt. londiocensis, solitavius, rodricensis., and molossinns) and scaj^u- 

 latus groups ( Pt. scapidatus and woodfordi) ; in the two latter species 

 these teeth are quite rudimentary, and at least in I'r. scupuhtus m^ 

 is fiometimes, but nr rarely, lost. 



Modifications of general shape (basal outline), and noticeable 

 reduction of size, of cheek-teeth. — The tyjjical Ptrropine shape and 

 size of the cheek-teeth lead, on the one side, through practically all 

 intermediate stages to the extremely heavy dentition of a Ft. pnela- 

 phon, and on die other through numerous transitions to the small 

 niid excessivel}- narrow cheek-teeth of a Ft. scapnlatus. Obliteration 

 of the posterior basal ledges of the cheek-teeth (a character which 

 of itself is perhaps indicative of a beginning degeneration of the 

 cheek-teeth) is rather often associated with a distinct reduction of 

 the size of the teeth : Ft. r/culdi, epalai-iuf, macrotia, poUocephalux. 

 The cheek-teeth are small but not much narrower than usual in 

 Ft. niolossiiii's; peculiarly sjiortened, witli rounded corners, in P/. 

 papuKHUs and )icohdjcrnici'..^if\gs. 9C', 101) ); and so much shortened 



