Measurements.—Average and extreme measurements of six females are as follows: Length of head and body, 80.8 (77-106); hind foot, 17.2 (16.0-18.7); ear, 12.7 (11.5-14.0); length of forearm, 49.3 (42.9-53.8). Average and extreme measurements of skulls of five females are as follows: Greatest length of skull, 31.8 (30.8-33.3); condylobasal length, 29.7 (28.6-32.4); zygomatic breadth, 18 (17.2-20.0); breadth of braincase, 12.6 (12.4-13.2); postorbital breadth, 8.3 (8.0-8.9); length of maxillary tooth-row, 10.1 (9.4-10.4); length of mandibular tooth-row, 11.7 (10.8-12.2).
Remarks.—On Choiseul Island Melonycteris aurantius was taken at the same locality as its congener, Melonycteris woodfordi.
Externally, M. aurantius resembles M. woodfordi. These species are the same size, but the former is brighter in color (nearly orange in adults) than the latter, which is Wood-Brown dorsally. Internally, differences between M. aurantius and M. woodfordi are more obvious. In the skull of M. aurantius, the postorbital region is expanded (measuring about 8.3), whereas in M. woodfordi the postorbital region is constricted. Furthermore, in lateral aspect the posterior portion of the skull of M. aurantius is down-turned and the angle of the facial axis with the basicranial axis is much more acute than in M. woodfordi.
The number of upper incisors is highly variable in the six specimens of M. aurantius that I have examined. In two specimens an extra tooth has erupted just anterior to I2 and there is a total of six upper incisors. In two other specimens an extra tooth has erupted in front of I2 on one side but not the other. I could find no trace of an extra tooth in the remaining two specimens.
Practically nothing is known about the natural history of M. aurantius, or, indeed, that of either of the other two species of this genus. One field collector (Temple, in litt.) for the Bishop Museum reported that he obtained both M. aurantius and M. woodfordi in the same mist net in one night. The holotype, an adult female, was lactating when obtained in October.
Melonycteris woodfordi (Thomas)
1887. Nesonycteris woodfordi Thomas, Ann. Mag. Nat. Hist., ser. 5, 14:147, February, type from Shortland Island; 1887, Thomas, Proc. Zool. Soc. London, p. 324, March 15; 1888, Thomas, Proc. Zool. Soc. London, p. 476, December 4; 1898, Trouessart, Catalogus Mammalium ..., 1:90; 1899, Matschie, Die Megachiroptera ... naturkunde, p. 91; 1904, Trouessart, Catalogus Mammalium .., Suppl., p. 66; 1907, Miller, Bull. U. S. Nat. Mus., 57:74, June 29; 1912, Andersen, Catalogue of the Chiroptera ... British Museum, 1:792, from Alu, Shortland, Fauro, and Guadalcanal; 1931, Sanborn, Publ. Field Mus. Nat. Hist., Zool. Ser., 18:23, February 12, from Russell Island (Pavuvo); 1954, Laurie and Hill, List of land mammals of New Guinea, Celebes and adjacent islands, p. 45, June 30.
1953. Melonycteris woodfordi, Pohle, Z. Säugetierk., 17:130, October 27, from Bougainville Island; 1966, Phillips, Jour. Mamm., 47:23, March 12, from Choiseul.
Specimens examined (three males and one female; in alcohol).—Choiseul, in April, 23413-14, 23434, 23275.