The genus 7ole is not marked by any very striking characteristic beyond the sharp carination of the upper mandible. In many respects it is intermediate between Hemixus and Pycnonotus but differs from both in the point above noted.
In Iole the feathers of the crown are slightly lengthened but they do not form a crest The bill is about three-quarters the length of the head and when viewed laterally is of much the same shape as that of Hemiancs (fig. 75, p. 375). The nuchal hairs are short. In Iole there are generally numerous hairs springing from the back but in Iole nicobariensis these hairs are very inconspicuous and on this account Blyth proposed the generic name Ixoocincla for this species, and if it is retained the specific name would then be virescens Blyth. If, however, a careful examination is made these hairs will be found, though they are short and not numerous. Although, therefore, somewhat aberrant, I retain it in the genus Idle. Sharpe retained the name Ixocincla for the other species of Iole and placed Ixocincla virescens of Blyth in the genus Hypsipetes (Microscelis) but in making both these changes he was, of course, quite incorrect.
Key to Species.
A. Lower plumage streaked Iole malaccensis, p. 404.
B. Lower plumage not streaked.
a. Crown and upper plumage uniform in colour.
a1 Entire lower plumage bright yellow. Iole icterica, p. 405.
b1 Lower plumage dull yellow Iole olivacea, p. 406.
b. Crown distinctly darker and browner
than the back Iole nicobariensis, p. 408.