370 



EMBALLOHtJRIDJE. 



the lining membrane is deeply wrinkled. The mouth of the sac is 

 formed by two raised edges, whereof one is higher than the other, 

 and when the wing is at rest lies over the other and closes the sac ; 

 but when the wing is extended the margins of the aperture are 

 separated and the sac opened. 



Eeinhardt, who examined many specimens of SaccopUryx canina, 

 both living and recently killed, remarks that the bag is provided 

 with particular muscles, on the contraction of which it must open ; 

 for in the alar membrane are seen fine muscular fibres which run 

 from the edges of the aperture in a direction parallel with the outer 

 edge of the alar membrane, partly towards the body, partly towards 

 the thumb. 



The development of this alar glandular sac (peculiar to this genus) 

 in males only indicates that it is a secondary sexual character, ana- 

 logous to the throat-pouches of Taphozous, the frontal sacs of Phyl- 

 lorhina, and other glandular organs found in the males only of many 

 species of Chiroptera*, all of which secrete an oily substance of 

 strong odour, which is probably of use in attracting the females. 



Synopsis of Siihr/enera and Species. 



a. Wing-sac opening along the forearm on 



the outer side of the antebrachial mem- 

 brane ; eai-s narrowed above, emarginate 



externally, tragus abruptly truncated 



above ; wings from the tibiae or from 



the ankles ; preniaxillary bones without 



internal oblique process, facial bones 



flattened ; anterior margin of the orbit 



in a vertical line with the second upper 



premolar Subg. SACCoPTERYxf. 



«. No longitudinal streaks on the fur of the 



back ; forearm about 1"'4 1. S. leptura, p. 371. 



/3. Two longitudinal streaks on the fur of 



the back ; forearm about 1"'8 2. S. hilineata, p. 372. 



b. Wing-sac opening near the anterior mar- 



gin of the antebrachial membrane, aper- 

 ture directed outwards; ears triangular, 

 roimded, close together or united by a 

 band across the face ; tragus rounded off 

 above ; wings from the tibia or from the 

 tarsus ; premaxillary bones with an in- 

 ternal oblique process ; facial bones me- 

 sially hollowed, laterally expanded above 

 in front of the orbits ; anterior margin of 

 the orbit in the same vertical line with 



the middle of the second premolar .... Subg. PeroptertxJ. 

 y. Ears separate ; wings from the distal end 



of the tibias ; forearm l"-8 3. S. canina, p. 373. 



* See my paper " Ou Secondary Sexual Characters in Ohiroptera," in P. Z. S. 

 J873, pp. 241-2.52. 



t Genus Saccopteryx, Ptfs. /. c, | Genus Peropteryx, Ptrs. /. c. 



