xlv 



PLASTIC CHARACTF.RS. 



(li) A tiift of hiiir on either side of the nock is in a large niimher 

 of genera distinctly differentiated in the males, being moi'e rigid, 

 unctuous, and brighter (or deeper or more saturated) in colour than 

 the surrounding fur (development of " neck-tufts ") ; or the -whole 

 of the fur across the foreneck and anterior portion of the chest 

 may be more rigid and more saturated in colour in males than in 

 females (development of a " ruff"), or the hair of the same region 

 of males may differ, if not in rigidity, at least in its richer colour 

 from that of females ; or (as is the case in some species of Pterojnis) 

 there may hardly be any sexual difference in the fur of tlie fore- 

 neck, but that of the nape of the neck (the " mantle") may be 

 distinctly more rigid in males, and in some of these species pale- 

 coloured from tip to base, whereas in females of the same species it 

 is pale-coloured only at the exposed tip, dark-coloured at the con- 

 cealed base {Fteropvs mariannus and conspic Hiatus groups). In 

 some genera of the Epomopliorus section the " neck-tufts " of tlio 

 males have, so to speak, moved higher np on the sides of the neck, 

 being situated one on each " shoulder," i. e. the region of the sides 

 of the neck immediately in front of the origin of the antebrachial 

 membrane (" shoulder brushes" or "epaulettes,'' hence the name 

 " Epomo-phorus," epaulette-bearer), at the bottom of a deep, pouch- 

 like depression in the skin (" shoulder pouches), each shoulder 

 brush being usually erectile and retractile at the will of the animnl 

 ("when erected the tuft had a vibratory movement," collector's 

 note on the label of a Micropteropus pnsilhis, British Museum). 



(4) Helatively rarely (Epnmops, Ht/psirpiaiJiiis, Epomopliorus) 

 males differ from females by the possession of one or several 

 pharyngeal air-sacs, a peculiarity very often, perhaps always, 

 combined with an enlargement of the larynx of the males (the 

 voice of Epomops and J/j/psignntJnis (both sexes? or males only?) 

 is described as a loud croaking, that of the latter i-ecalling the 

 croaking of the Ethiopian Giant Frog, liana occipitalis). In one 

 of the same genera {Hi/psignatlms) the muzzle and cranial rostrum 

 are much heavier in males, owing to the development in that sex of 

 a subcutaneous air-sac on either side of the muzzle and large 

 cutaneous folds on the extremity of the muzzle (the latter present, 

 but much smaller, also in females). 



lleviewed in each of the four natural sections of Megachiroptera 

 the secondary sexual characters are, briefly, these (diiferences in 

 size of canines and in zygomatic breadth omitted): — 



Rousettus section. — EiJolon : males with richer-coloured neck- 

 tufts (traceable, but smalhsr and less rich in colour, in females) ; 

 females, at least in two species (7ie?rM)n and sa/>«?Hm), conspicuously V 

 paler than males, liousettus : males as a rule with neck-tufts, 

 the unctuous hair sometimes forming a " ruff " across the foreneck. 

 Boneia: sexual characters unknown (females not on record). 

 Pteropus: fur of mantle often (not always) more rigid and unctuous 

 in males, softer and more spreading in females, in a few species 



