HyrSlGNATHUS. 



505 



Epmnops, tip more narrowly pointed ; small whitish tnfts at hase of 

 conch anteriorly and posteriorly (as in all Ei)omophorine bats). 

 No external tail (and no tail vertebrae). Interfemoral and calcar 

 as in Epomops. 



Membranes inserted posteriorly on middle or proximal half of 

 second (in Epomops on first) phalanx of second toe. Vertical fasciae 

 of mesopatagium fewer (26-34) and less crowded. PoJlex and 

 terminal phalanx of fourth and fifth digits distinctly shorter thiin 

 in Epomops. Subjoined the wing-indices of Hi/psl</7intJn(s (upper 

 row), calculated from measurements of seven adult individuals, 

 and, for comparison, those of Epomops (lower row). 



Sexual differentiation. — (1) Hammer-shaped form of muzzle and 

 cranial rostrum much more pronounced, cutaneous leaves at extremity 

 of muzzle and corresponding vertical ridge of cranial rostrum much 

 larger, and occipito-poUicalis muscle (one of the supporters of the 

 head, visible externally as a strong subcutaneous baud from point 

 of origin of antebrachial membrane, along either side of neck, to 

 sides of occiput) much stronger in males than in females. (2) Males 

 with two pairs of pharyngeal sacs, homologous with those of 

 Epomops, and -with a paired sac communicating with mouth beneath 

 upper lip and extending from extremity of muzzle on either side of 

 rostrum to halfway between eyes and ears ; larynx much larger in 

 males. (3) General size of males considerably larger. — No shoulder 

 pouches or epaulette-like hair-tufts in either sex. 



Habits, — Hammer-headed Bats are particularly abundant in the 

 mangroves and palms along the banks of the rivers, more rarely 

 seen in the forest (except at swampy places), but not infrequently 

 visiting the clearings of the human settlements at night in search 

 of ripe bananas, mango plums, and soursops (Anoua muricata). 

 The voice is a loud croaking, recalling that of the Ethiopian Giant 

 Frog, Sana occipitalis (Biittikofer, Ileisebild. Liberia, ii. p. 3G2, 

 1890; Bates, P.Z.S. 1905, i. p. 72). 



Affinities. — Hypsignathus has probably originated from a bat 

 which in all important characters was similar to Epomops (but 

 with the postdental palate not broadened quite to the same extent 

 as in Epomops). The only verj' essential cranial peculiarity of 

 HypsignatJius is the great enlargement of the rostrum, but this 

 modification is much more pronounced in males than in females, 

 and is in reality scarcely more than an excessive development of a 

 tendency already present in Epomops. The two genera, Epomops 

 and Hi/psi/jnathi's, exhibit the following four principal stages of 

 enlargement of the rostrum : females of Epomops, males oi Epomops, 



