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Show 422 THE MARQUIS OF TWEEDDALE ON BATRACHOSTOMUS. [May 15, the vicinity of Darjeeling, Tung-goo and Karen-nee in Burma, Malacca, Sumatra, Borneo, Java, and Mindanao. It was an a priori and a natural inference of many ornithologists that the bright-plumaged birds of the genus Batrachostomus must be males, and the grey dull-coloured birds either females or immature examples, or else that they belonged to totally distinct species; for the Batrachostomi exhibit two very distinct phases of plumage- the bright rufous or rufous bay (when adult), and the speckled, spotted, and striated grey and brown and rufous brown dress. So very different an aspect do individuals falling under either one or other of these two phases assume, that it was long before some authors suspected that they in fact belonged to the same species, though to the opposite sexes. This conclusion cannot even now be considered as placed beyond doubt (for tbe Frogmouths may be dimorphic) ; and it is therefore proposed to state and examine the evidence on which it rests. Bonaparte (Consp. i. p. 57. no. 2) seems to have been the first writer who announced that in the case of B. javensis the sexes differed ; for he remarks (I. c.) :-" Mas et fern, inter se colore differunt uti Scops asio differt a Sc. naevia auctorum." But his simile leads to the inference that he thought the rufous birds were males and the grey females. A few years later Prof. Schlegel (J. f. Orn. 1856, p. 460) propounded the general and more definite axiom that in all the Indian species of the genus Podargus (Batrachostomus) the males are grey, the females rust-coloured. At that time the Leyden Museum possessed examples of two Asiatic species, identified by the Professor as B. parvulus (ex Borneo and Malacca) and B. cornutus (ex Java, Sumatra, and Borneo); and to these species must Professor Schlegel's dictum be restricted, doubtless founded on numerous examples with the sexes determined by the Dutch collectors. Of B. parvulus ( = B. affinis, Blyth), ex Malacca and Borneo or Sumatra, I have not met with an example, in either grey or rufous plumage, of which the sexes had been determined by a competent collector. Yet, if B. affinis, Blyth, is but a slightly smaller form of B. castaneus, H u m e (of which there is little doubt), and consequently the rufous phase of Otothrix hodgsoni, then there is some confirmatory evidence of Prof. Schlegel's opinion that the grey birds belong to the male sex. Examples of B. cornutus, ex Sumatra and Borneo, in both plumages, with the sexes determined, fortunately exist in England, and bear out the Professor's conclusions. In the British Museum is preserved an example, ex Sumatra, in grey plumage, and marked as being of a male by its collector, Mr. Wallace. Count Salvadori (I. ci) describes a freckled rufous individual from Sarawak ; and the sex, as ascertained by the collector, is stated to be female. Two pairs of this species, collected in Banjarmassing by Motley, were examined by Mr. Sclater; and he observed (P. Z. S. 1863, p*. 212) that " the sexes are very different in colouring, the male being minutely freckled with brown and black, and the female bright rufous. Horsfield's figure represents the female." As regards the remaining Asiatic species there is also some evidence on this point. A bright rufous example |