OF THE BEITISH ISLANDS. 65 



ORDER RALLIFORMES. THE RAILS AND FINFOOTS. 



THE Rails and their allies form a comparatively well-defined and somewhat 

 isolated group, the affinities of which are by no means clearly determined. 

 They have been more or less closely associated with other groups, such as the 

 Bustards, the Cranes, the Game Birds, the Sand-Grouse, the Grebes, and so on, 

 according to the importance attached to certain characters by various system- 

 atists. Their sternum contains one notch only on each side of the posterior 

 margin ; but, unlike the Galliformes, the opisternal process is not perforated to 

 receive the base of the coracoids. In the modification of their cranial bones 

 they are schizognathous, whilst their nostrils are holorhinal. The dorsal 

 vertebrae are heterocoolous. Amongst their external characters may be men- 

 tioned the following : The oil-gland is tufted ; the af tershaft is in most 

 cases present ; the toes are long and slender, sometimes furnished with 

 webs and scallops, the hallux slightly elevated ; the metatarsus is rather 

 short. The bill varies considerably in size and shape. The primaries are ten 

 in number ; the rectrices vary from twelve to eighteen in number. So far as 

 is known the young are hatched covered with down, and able to run and swim 

 shortly after leaving the shell ; although in the Finfoots (Heliornithidae) the 

 young are reputed to be hatched naked. Nothing definite, however, appears to 

 be known relating to this portion of their economy. Moult variable in some 

 species once in autumn only ; in others in spring and autumn. In the single- 

 moulted species the nuptial plumage is assumed by abrasion and increased 

 brilliancy. 



The birds in the present order number upwards of two hundred species and 

 subspecies. These have been divided into two well-marked families by Dr. Sharpe, 

 the most recent monographer of the group : one of these is well represented in 

 the British Islands. It seems probable, however, that the Mesitidae (containing 

 but one species) of Madagascar will have to be included in the present order. 

 These birds are cosmopolitan with the exception of the Polar regions. 

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