46o IRIS— IVORY-BILL 



body, but generally now restricted to the organs of the Digestive 

 System. 



IRIS (plural Irides), the coloured ring surrounding the pupil of 

 the Eye. 



IRRISOR, the generic name, since adopted as English, pro- 

 posed by Lesson in 1831 {TmiU d'Orn. p. 239) for an African bird, 

 the Ujmpa crythrorhynchus of Latham, Avhich had hitherto been so 

 variously assigned that its affinities were uncertain, and so they 

 remained until Dr. Murie {Ibis, 1873, pp. 181-211, pis. v.-vii.) 

 proved that the surmise of its original describer and of Strickland 

 {Ann. Nat. Hist. xii. pp. 238-243) in referring it to the Upupidx 

 (Hoopoe) was not far wrong, though, along with BUnojMmastus an 

 allied genus named by Andrew Smith and established by Jardine 

 in 1828 {Zool. Journ. iv. p. 2, pi. i.), it might be justifiably placed in 

 a separate Family.^ No fewer than 10 species of Irrisor, one of 

 which has been further generically distinguished as Scoptelus, have 

 been described, and 3 of Ehinopomastus ; but perhaps there are 

 not I'eally so many. All are African, recognizable by their more 

 or less curved bill, glossy purple or steel-blue plumage, with a white 

 patch on the wing, and white on at least the outer feathers of the 

 tail, which is commonly elongated. They are Avholly arboreal in 

 their habits, thereby differing from the Upudidx, and unceasingly 

 seek their food in the insects that frequent the bark of trees. The 

 commonest species of the Cape Colony, /. erythrorhynchis has, ac- 

 cordhig to Mr. Layard {B. S. Africa, p. 73), a harsh cry, and is 

 called by the Dutch KacMa, meaning "chatterer." Another, It. 

 cyanomelas, also occurs in South Africa. 



ISCHIUM, or Os ischii, the posterior and ventral, or middle 

 bone of the three that form each half of the Pelvis, and meet at 

 the acetabulum or cup which receives the head of the Femue. 



IVORY-BILL, an abbreviation of Ivory-billed Woodpecker, 

 so called from the colour of its beak, I'icus or Campephilus pnin- 

 cipalis, the largest 

 species of the 

 Family inhabiting 

 the United States 

 of America, and 



except its more Campephilus principalis. (After Swainson.) 



southern relative P. or C. imperialis the largest of the PicidR'. 

 Though said to have been met with in Maryland, North Carolina 

 seems to be the northern limit of its ordinary range in the east, and 



'' In tins case tlie name of the Famil}' should he Family lihinopomastidic 

 from the oldest genus in it, not Irrisoridse, as often given. 



