18 PTEEOPODIDiE. 



fruits are always obtainable ; and there are also found the largest 

 species of the genixs, while the smallest, and those provided with 

 long woolly hairs extending thickly upon the extremities appear to 

 be confined to the small wind-swept oceanic islands situated towards 

 the extreme northern or southern limit of the distribution of the 

 family. 



So large are the number of species of this genus, and so closely 

 are they related to one another by different characters, that it is 

 extremely difficult to ai range them according to their natural 

 affinities or to divide the genus into sections. At first sight it 

 might appear possible to divide them according to the quality and 

 distribution of the fur, or by the form of the skull and teeth ; but 

 the occurrence of such forms as Pteroj^us molossinus, which has the 

 quality of fur and ears characteristic of one section, the distribution of 

 fur of another, and the teeth of a third, or of Ft. poliocephalus, which 

 resembles one group of species in the quality and distribution of the 

 fur, while it agrees with a very different section in the development 

 of the ears and teeth, renders a natural arrangement of the species 

 in a linear series quite impossible. 



The following Sj-nopsis must therefore be considered chiefly as an 

 index to the species, the position of each species with regard to the 

 others not necessarily indicating its special affinities, which are 

 pointed out in the general description. 



Synopsis of the Species. 



a. Fur soft and woolly ; ears generally shorter than 

 the muzzle, more or less concealed by the long 

 fm-. 

 a'. Legs densely clothed as far as the ankles or backs 

 of the feet with erect woolly hair (naked in 

 Pt. molossimis only). 

 a". Fm' of the back nearly as long as that of the 

 neck ; ears shorter than the muzzle. 

 a'". First upper premolar very small or deci- 

 duous ; premolars and molars without pro- 

 minent cusps. 

 rt*. Ears very short, clothed with long hairs, 

 and concealed by the long fur of the 

 head ; legs clothed above and beneath. 



1. Larger : forearm 6"-2 ; ears narrow, 



acutely pointed Pt. vulgaris,-a. 23. 



2. Smaller : forearm 3"7 ; ears shorter, [p. 24. 



obtuse ; fur exceediEgly fine and soft . Pt. rubricollis, 

 b\ Ears longer, half clothed, projecting 

 slightly beyond the fur of the head ; legs 

 half naked beneath, 

 t'. Legs clothed as far as the ankles. 



3. Collar not well defined, passing gra- 



dually into the light-coloured fur of [p. 25. 



. J},'' ^^'^^ Pi- dasymaUm, 



4. Collar very distinct, bright yellow or 



yellowish white Pt.formosus,-^.2&, 



