Heretofore, the generic name _Nesonycteris_ has been applied to the species in the Solomons, whereas _Melonycteris_ has been restricted to the one species in the Bismarck Archipelago and New Guinea. Andersen (1912:792) judged that _Nesonycteris_ was clearly distinct from _Melonycteris_ on the basis of two characters (loss of a claw on the second digit and loss of the inner, lower incisors). On the other hand, he noted striking similarities in general cranial features, dentition, palatal ridges, tongue, and external appearance of the two genera. Pohle (1953:131) synonymized the two but Laurie and Hill (1954:45) considered them distinct. I have suggested previously (Phillips, 1966:26, 27) that characteristics used to distinguish between _Melonycteris_ and _Nesonycteris_ are of less than generic value. Variability of number of incisors in the upper jaw of specimens of _Melonycteris_ (and in other macroglossine genera, as well) indicates a lack of selective pressure for either increase or decrease in number of incisors. Furthermore, the loss of the small claw on the second digit might not be important because, as Bader and Hall (1960:15) have pointed out, limbs of bats vary more in phenotypic expression than do other parts of the skeletal structure. The discovery of a new species (_Melonycteris aurantius_) in the Solomon Islands sheds additional light on the problem. Although _M. aurantius_ possesses the distinguishing characteristics of the genus "Nesonycteris," the species closely resembles _Melonycteris_ in other features. Similarity in structure of hair of _Melonycteris_ and _Nesonycteris_, as first reported by Benedict (1957:293), also supports the argument for synonymy (see Phillips, 1966:26). _Melonycteris aurantius_ lacks a small claw on the second digit and has only two lower incisors. In these ways this species is like _woodfordi_, which also is restricted to the Solomons. On the other hand, the structure of the skull of _M. aurantius_ is like that of _M. melanops_, which is the species found in the Bismarck Archipelago. Although _melanops_ is not yet known from the Solomon Islands, I have included it in the following key. Key to Known Species of _Melonycteris_ 1. Ventral surface darker than dorsum, but not strongly contrasting with it; lacking a small claw on the second digit, 2 1´. Ventral surface nearly black, strongly contrasting with dorsum; small claw on second digit, =Melonycteris melanops= 2(1´). Pelage bright, Cinnamon-Rufous; postorbital region of skull expanded (about 8.3 wide), =Melonycteris aurantius=, p. 816 2´. Pelage dark, near Wood-Brown or Cinnamon; postorbital region of skull constricted (about 7.5), =Melonycteris woodfordi=, p. 816