Dicruridse and their Arrangement. 71 



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- 

 murus, 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. brachyphorus, D. 

 malabaricus, D.p/aturus (ex Sumatra), and D . paradiseits 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. grundis ; 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 different 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 

 Dissemw'us, 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 geuus in his 'Analyse,' 1816— that is, at a date 

 anterior to and in a work different from the one quoted by Mr. Sharpe. 



