— 4 — 



questiou, and it is thus possible and indeed probable that in- 

 vestigations of the bird-kingdom on the eastern slopes of Mount 

 Elgon will include under another name such birds as I, owing 

 to want of material, have been obliged to place under forms at 

 present known. 



The main object of ornithology is by no means to describe 

 new species and forms, though this task can be a grateful and 

 pleasant one, but a department which is at least quite as im- 

 portant for the knowledge of the "form circles" and their distri- 

 bution is that concerned in the critical examination of the 

 numerous forms already described. In conjunction herewith 

 one is liable to be lead at times into the difficult and com- 

 plicated question of latitude of variation — if I may call it 

 so — of the various forms, and one can then be in a position 

 to establish how forms, which have been considered good, are 

 only different variations of one and the same form. In order 

 that something like a good result in matters of this kind be 

 attained, it is, however a condition sine qua non that there is 

 an extensive material for comparison at one's disposal — which 

 has so often been emphasised — , and that one is quite familiar 

 with the rich and ample litterature of later years. On this basis 

 it is possible to contribute in a greater or lesser degree to the 

 solution of some of the problems of ornithology and modern 

 systematisation: form circles and their extent, the affinity of the 

 various groups of birds, etc. even if this should sometimes happen 

 in a manner which demands the abandonment and rejection of 

 previously approved forms or the description of new ones. This 

 task on account of our uncertain knowledge of the conception of 

 species and forms from a genetic point of view, is however very 

 difficult and it therefore often seems as if the labour expended 

 and the result attained, does not stand in reasonable proportion 

 to each other. 



It does not come within the scope of this work to analyse 

 all the different opinions concerning forms, variations or races, 

 therefore I will only give a few of the latest. J o r d a n s has 

 (Die Vogelfauna Mallorcas, 1914, p. 34) expressed the opinion 

 that the natural species is the total sum of all forms. The latter, 

 sometimes called subspecies, or races, severally form geographical 

 units and now as the forms, belonging to one and the same 

 „form circle" are among themselves more closely related to each 

 other than to those belonging to an allied circle, the circle of 

 forms make a natural genealogical circle. — Stuart Baker 

 (Bull. Brit. Orn. Club, vol. XL, 1920 p. 80) has defined the con- 

 ception of subspecies in the following manner: „A subspecies is 

 a geographical race or variation, differing in some respect from 

 the form first described as a species, yet linked with it by other 

 intermediate forms found in intervening areas. It is essential 

 however, that the variation before it is named shall be proved 



