770 RECTUM— REDBACK 



(Capito) on the one hand and the PUFF-BIRDS (Monacha) on the 

 other. Though the smaller number may be a later and higher 

 stage of the tail's development, it certainly does not confer a higher 

 morphological rank on the forms that bear it, as is shewn by the 

 fact that the majority of PlCARi^ have but 5 pairs, and also some of 

 the lower Passeres as Acanfhidositta and Xenicus, while it is certain 

 that the possession of more than 6 pairs is not an ancestral feature, 

 the increase being a comparatively recent acquisition. Indeed the 

 number of Rectrices seems to have but little signification, very 

 nearly- allied species differing in this respect. Thus of Oreocinda 

 (Thrush) two species have 7 pairs, and all the rest 6. Among the 

 Cormorants the common Phalacrocorax carlo has 7 pairs and the 

 smaller F. graculus (Shag) 6 pairs. Still greater diversity obtains 

 among the SNIPES, the oi-dinary species of the Old World, Gallinago 

 cmlestis, has 7, that of North America, G. wilsoni (otherwise not 

 readily distinguished from the former) has 8, as also has G. major, 

 while G. gallinula, the Jack Snipe, but 6, though in the last two 

 cases accompanied by osteological differences, and the Pin-tailed 

 Snipe of Asia, G. sfenura, sometimes exhibits 14 pairs. Several 

 other similar cases are on record and many must exist that have 

 not been detected. A difference too may depend upon sex, as 

 with the Peacock, which has 10 pairs, being one more than the 

 Peahen. 



Of the varied forms and functions of the Rectrices there is little 

 need to speak. The difterences displayed by the first are obvious 

 to all who have the least acquaintance with Birds. The forked tail 

 of a Swallow is proverbial, and the pointed tail of a Parakeet 

 hardly less familiar, while the erect tail of the Cock with its gallant 

 streamers affords a striking contrast to the flattened tail of the 

 Goose that feeds beside him in the poultry-yard. Similarly as to 

 function : in the Peacock, QuEZAL and some other birds the 

 rectrices serve but as a support to the showy train that covers and 

 hides them : in the Woodpeckers, Tree-creepers, and many 

 forms not allied to either, they are of the greatest importance in 

 the bird's economy, as without their support it would be unable to 

 obtain a living ; but many are the cases in which ingenuity is at a 

 loss to assign the reason for some remarkable peculiarity ofitered by 

 the Eectrices. 



RECTUM, the portion of the intestine (Digestive System, 

 p. 138) between the insertion of the C.^CA and the CLOACA. Birds, 

 the Batitm and Palamedea excepted, have no colon, and the Rectum 

 descending along the right kidney is generally shorter than the 

 distance from the upper end of the kidneys to the cloaca. In the 

 Ostrich, however, it is of enormous length (p. 140) and width. 



REDBACK, a name applied in North America to the Dunlin 



