

11 



remain therefore unknown, and can only be supposed to have resembled those of other 

 Drepanididse. The external features, except the coloration of the plumage, are entirely 

 like those of the other Drepanididse. The shape of the non-serrated bill, the opercu- 

 lated nostrils, their shape and size, agree in every detail with the corresponding parts 

 of Hemignathus procerus and Vestiaria. The tenth primary is occult; the tip of the 

 wing is formed by the eighth, seventh, and sixth primaries, the ninth equals the 

 fifth in length. Some of the marginal axillary feathers are fluffy and elongated. The 

 rich yellow feathers of the lower back are extremely fluffy and long. The twelve tail- 

 feathers have obliquely pointed tips, but the tail, when spread out, is slightly rounded. 

 The metatarsus is covered in front with a row of five or six transverse scales, which are 

 partly fused with each other ; the lateral side is protected by one long scute, and 

 distally by several small scales, and the same applies to the median side. Whether 

 there was a prominent ridge on the posterior side of the metatarsus cannot be 

 determined with certainty. The second toe is the shortest, the middle one the 

 longest, the hallux the strongest. The claw of the hallux is by far the longest and 

 strongest. 



There remains the question, whether the resemblance in shape and coloration of the 

 whole bird to Acrulocercus is accidental or a case of mimicry ; and if it is mimicry, 

 which of the two birds is the original and which is the copy? The fundamental differ- 

 ence, at first sight almost imperceptible, between the serrated bill of the Meliphagine 

 Acrulocercus and the smooth bill of Drepanis adds to the interest of the case. Of 

 course the question cannot be settled conclusively, but the following arguments may 

 help to a solution. 



Both birds are aberrantly coloured, differing from their respective relations. All the 

 Drepanididse, except D. pacijlca, are either of a uniform dull green, or a beautiful red, 

 or red mottled with black, or, lastly, indifferently grey and brown like Oreomyza. 

 Vivid yellow, combined with black and varied by a few white patches, which is the 

 colour of Drepanis pacifica, appears abnormal in this family. D. pacifica differs 

 likewise from its allies in being by far the largest and strongest. 



Acrulocercus, a truly Meliphagine bird, on the other hand exhibits colours which 

 occur also in many other Meliphagidas, although none of these, except Pogonomis, are 

 chiefly black with yellow and white ornaments. Moreover, yellow tufts in the axillary 

 region are a favourite ornament among the Nectariniidse, which are undoubtedly allied 

 to the Meliphagidas. Lastly, there are three species of Acrulocercus, all greatly 

 resembling each other and distributed over most of the Hawaiian Islands, while there 

 was apparently only one black-and -yellow Drepanis. 



These arguments seem to vouch for the probability of Acrulocercus being the original, 

 Drepanis pacifica the imitating form. However, it must not be forgotten that the 

 Meliphagidas are, in the Hawaiian Islands, represented only by Acrulocercus and 

 Chcetoptila, and that consequently the four species may be looked upon as strangers 

 and intruders, while the Drepanididas are present in considerable numbers as species 

 and genera, and may therefore be regarded as more indigenous. 



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