494 . Mr. 0. Thomas on 



2. Higher, divided in the centre by a notch, tlie median 

 line of which tends to be grooved, naked, and of a different 

 texture to the rest *. 



3. Much higher, the two divisions connected with each 

 other, and surpassed above, by a median, smooth, and naked 

 membrane, which is folded to form a Y-shaped groove on its 

 anterior surface f. 



Tiiere is, however, a nearly complete continuity of develop- 

 ment from one extreme to the other, so that the position of 

 individual specimens may occasionally be in doubt. 



The baculum in Nyctophilus has a broad stout bifid base 

 and a downwardly curved shaft, generally about 2^-3 times 

 the length of the breadth of the base. Its tip may be either 

 simple and slightly flattened, or bifurcate. 



The species are here taken geographically, beginning with 

 the west and passing first eastwards and then to the north 

 and north-west. 



1. Nyctopliilus major, Peters. 



Abh. Ak. Berl. 1860, p. 125 (1861), ex Gray, Voy. Ereb. Terr. pi. xxi. 

 fig. 2 (plates prepared in 1845, not published till 1875). 



Size largest of the genus, a skull measuring 19"8 mm. in 

 greatest length ; maxillary tooth-row 7'3. Bullae fairly 

 large, 4*3 mm. 



No spirit-specimens available, but the nose-leaf appears 

 from skins to be of the less-developed type. No bacula 

 seen. 



Hah. Western Australia. Type from Perth. Other 

 specimens from King George's Sound, (Southern Cross, &c. 



Type. B.M. no. 44. 7. 9. 20. 



2. Nyctophilus geoffroyi^ Leach. 



Trans. Linn. Soc. xiii. p. 78 (1822). 



N. australis, Peters, Abh. Ak. Berl. 1860, p. 123, plate (1861). 



Size small or medium. Ears proportionally large. Nose- 

 leaf of the most highly developed type, as described under 

 3, above. Baculum with the normal broad bifid base and 

 simple slightly flattened tip. BuUse large. 



Three subspecies may be recognized : — 



* Dobson's figure (Catalogue, pi. xi. fig. 7) corresponds to this degree 

 of development, but is slightly exaggerated towards the third type. 



t Peters's figure o£ Ki/ctojyhilus australis (Abh. Ak. Berl. 1860, plate, 

 fig. 2) shows this leaf, but does not indicate the Y-shaped groove seen in 

 the best-developed specimens. 



