986 TREE-CREEPER 



from observation, and a considerable mass of material is commonly 

 used to stuff up the opening partly and give a sure foundation for 

 the tiny cup, in which are laid from six to nine eggs of a trans- 

 lucent white, spotted or blotched with rust-colour. The Tree- 

 Creeper inhabits almost the whole of Europe as well as Algeria, 

 and has been traced across Asia to Japan. It is now recognized 

 as an inhabitant of the greater part of North America, though for 

 a time examples from that part of the world, which differed slightly 

 in the tinge of the plumage, were accounted specifically distinct 

 (c/. Ridgway, Froc. V. S. Nat. Mus. 1882, pp. 111-116). It there- 

 fore occupies an area not exceeded in extent by that of many 

 Passerine birds, and is one of the strongest witnesses to the in- 

 separability of the Holarctic Fauna. 



Allied to Certhia, but wanting its lengthened and stiff tail- 

 feathers, is the genus Tichodroma, the single member of which is 

 the Wall-Creeper, T. muraria, of the Alps and some other moun- 

 tainous parts of Europe and Asia, and occasionally seen by the 

 fortunate visitor to Switzerland fluttering like a big butterfly 

 against the face of a rock, conspicuous from the scarlet-crimson of 

 its wing-coverts and its white-spotted primaries. Its bright hue 

 is hardly visible when the bird is at rest, and it then presents a 

 dingy appearance of grey and black. It is a species of wide range, 

 extending from Spain to China ; and, though but seldom leaving 

 its cliffs, it has wandered even so far as England.^ 



The genus Certhia as founded by Linnaeus contained 25 species, 

 all of which, except the two above mentioned, have now been 

 shewn to belong elsewhere ; and for a long while so many others 

 were referred to it that it became a most heterogeneous company. 

 At present so few are the forms left in the Family Certhiidx 

 that systematists (c/. Gadow, Cat. B. Br. Mus. viii. pp. 322-340) 

 are not wanting to unite it with the Sittidse (Nuthatch), for the 

 two groups, however much their extreme members may differ, are 

 linked by forms which still exist, and little violence is done to the 

 imagination by drawing upon the past for others to complete the 

 series of descendants from a common and not very remote ancestor, 

 one that was possibly the ancestor of the Wrens as well. Two 

 things, however, have especially to be noticed here. The Certhiidse 

 have not the least affinity to the Picidse (AVoodpeckkr), but are 

 strictly Passerine, and also that the Australian genus Climaderis 

 may possibly not belong to them. 



1 Merrett [Pinax, p. 177) in 1667 included it as a British bird, and tire 

 correspondence between Marsham and Gilbert White {Proc. Nor/, and Norw. 

 Nat. Soc. ii. p. 180) proves that an example was shot in Jlorfolk, 30th October 

 1792 {of. Stevenson and Southwell, £. Norf. iii. p. 380, pi. v.), while anotlujr is 

 reported {Zoologist, ser. 2, p. 4839) to liavo been killed in Lancashire, 8th 

 May 1872. Its reputed occurrence in Abyssinia seems doubtful. 



