BIFASGIATED LARK. 107 



The egg is very large — twelve lines by eight; the ground colour 

 like that of C. Duponti, but the brown blotches smaller, and far 

 more closely distributed, especially towards the broader end. It would 

 not be easy to select it out of a series of some varieties of Lanius 

 excubitor." 



Mr. Tristram has described in the same paper another Certhilauda 

 closely allied to this, under the name C. Salvini. The sterna, drawings 

 of which are given, are certainly very different, even in important 

 osteological characters. This bird is shorter by one fifth of an inch, 

 more slender, and has a broader white band on the secondaries than 

 C. bifasciata. Mr. Tristram suggests, however, it may be only a local 

 race, although this idea is rather negatived by the fact that both he 

 and Captain Loche had independently arrived at the conclusion that 

 these were two species, and that the smaller one, though confined 

 to the southern and south-eastern districts, never being found in the 

 central or western, yet did not supplant the common bird in the 

 districts where it occurred. 



These observations lead Mr. Tristram into a very interesting discus- 

 sion of the now exciting question of the variation in species. Though 

 tempting, I have not room in this work to follow him in his remarks, 

 but I must refer the reader to the first volume of the "Ibis," p. 

 429, et seq. 



I may remark, however, that while Mr. Tristram thinks that obser- 

 vations he made on the Larks and Chats of North Africa, illustrate 

 the views of Mr. Darwin and Mr. Wallace upon this subject, he 

 distinctly repudiates the possibility of such a law acting beyond the 

 sphere of species and race. "I do not," he says, "for a moment 

 mean to imply that such birds as Rhamphoceris clot-bey have been 

 developed out of any known European form, or that we are to pre- 

 sume so far to limit Creative Power, as to endeavour to explain the 

 growth of desert species universally by the development of individual 

 peculiarities." 



It will be well for science and themselves, if all naturalists will 

 stop at the boundary line thus drawn by Mr. Tristram. That species 

 do vary, no naturalist denies. That they do this beyond the pecu- 

 liarities by which the species is recognised, no one has ever yet proved. 

 "Naturam expelles furca, tamen usque recurret." 



The adult male and female of the Bifasciated Lark do not differ 

 in their plumage. The upper parts are of a light chesnut, or isabelle 

 colour, tending more to grey on the top of the head and nape, and 

 the upper tail feathers being darker chesnut, with lighter borders. 

 The . auric ulars are mixed chesnut and black, and there is a slight 



