83 
Dicruridse and their Arrangement. 
the gradation of the quills there is some analogy; but in Irena 
the 3rd^ 4th, and 5th are usually equal and longest, whereas 
in Dicrurus the 3rd is generally shorter than the 4th and 5th. 
Beyond these points all resemblance ceases. The tarsus and 
feet are short and weak in Irena ; the toes and nails are 
singularly slender for the size of the body; and the outer toe 
is free, whereas in Dicrurus it is ankylosed up to the first 
joint. The tail consists of twelve rectrices, and not of ten; 
and this character of itself removes Irena from the Dicruridse, 
according to Mr. Sharpens own definition*. The plumage is 
of a totally different character. The skin in Irena is especially 
tender; in Dicrurus it is exceedingly tough. In Dicrurus the 
sexes wear the same plumage, even the ornate plumes; in 
Irena the male has a brilliant, and the female a sombre attire. 
Every species of Irena has a number of fine nuchal hairs, 
which are wanting in Dicrurus. This last character (unknown 
to Blyth and Jerdon), together with the short and weak feet, 
indicates a great affinity to Criniger. The Dicruri are insec¬ 
tivorous, some even killing small birds, whei'eas Irena is 
frugivorous. The structure of the sternum in Dicrurus^^y 1 
believe, different from that of Irena. The notes of Irena are 
those of Oriolus, and have no similarity to those of Di¬ 
crurus. If we turn to the characters whereby Mr. Sharpe 
differentiates Irena from the other genera of the Dicruridse, 
the terms will be found to be not altogether exhaustive or 
satisfying:—Tail square ; plumage of upper surface en¬ 
amelled.^^ 
Irena criniger. —Mr. Sharpe separates Bornean and Su¬ 
matran examples from the Malaccan /. cyanea under this 
new title, solely on the ground that in I. criniger the under 
tail-coverts are produced to the very end of the tail,^^ while 
in I. cyanea they fall short of the tip of the tail by half an 
inch.^^ In a Malaccan example (mus. nostr.) the under tail- 
coverts reach within one eighth of an inch of the tip of the 
rectrices. But even if the character holds good, how can I. 
criniger, according to Mr. Sharpe’s own views, rank higher 
than a subspecies ? The presence of nuchal hairs is not men- 
^ See the characters of Dicruridae {t. c. p. 4). 
g2 
