71 
Dicruridse and their Arrangement. 
nasal and frontal plumes and the rectrices are the parts which 
exhibit the greatest tendency to specific development or vari¬ 
ation ; and in some^ such as in the species falling under Disse- 
muruSj the structure of the outer pair of rectrices is very un¬ 
stable, the tendency being to revert back to the fully webbed 
feathers. I have met with examples of D. hrachyghorus, D. 
malabaricuSy D.platurus (ex Sumatra), and D.paradiseus with 
the outer pair of rectrices flattened and fully webbed through¬ 
out their length, as is always the case in D. megarhynchus 
and D. lophorhinus. The nasal and frontal plumes occur, 
according to the species, in every stage of development, 
reaching to a fully webbed, lengthened, and voluminous 
overhanging frontal crest in D. grandis ; while in Chibia 
hottentotta the nasal plumes are even more lengthened, but the 
webs of the longest are obsolete. A parallel instance in other 
genera occurs in Edolius forficatus, in which species the 
nasal plumes are developed into a short erect bunch of webbed 
feathers, while in Buchanga andamanensis the erect .shafts are 
webless. The tendency of the outer pair of rectrices to twist, 
whereby the full growth of the inner is probably checked, 
is indicated in every species in which the outer pair is ab¬ 
normally lengthened relatively to the remaining pairs. The 
amount and distribution of the metallic burnishing on parts 
of the plumage is another direction in which specific variation 
exhibits itself. Now if, instead of an exaggeration or abor¬ 
tion of a frontal crest for instance, the variation of a species 
showed itself by some constant mark of a difierent colour, 
or even shade of the same colour, the specific distinctness 
of the species possessing it would be readily admitted. Mr. 
Sharpe ignores such differences—for example, in the genus 
Dissemurus, and unites all the races which have been sepa¬ 
rated by previous authors ; and yet he makes a new species, 
D. ceylonensis, upon grounds even less sufficient. 
Dicrurus*.— Under this genus Mr. Sharpe places three 
African species, and associates them with two Philippine and 
a Malaccan species which extends to the Himalayas. We 
Vieillot established this genus in his ^Analyse,’ 1816—that is, at a date 
anterior to and in a work different from the one quoted by Mr. Sharpe. 
