414 BULLETIN 15 3, UNITED STATES NATIONAL MUSEUM 



into damarensis; birds collected at Akanjande appear somewhat 

 intermediate * * ." 



Sliarpe's form media7ius -'^ is merely a small female of the typical 

 race. These hornbills vary greatly in size, as may be seen from 

 the table of measurements of the Mearns-Frick series. Lonnberg^® 

 has called attention to the fact that the bill is shorter in birds living 

 in regions of hard soil than in specimens from places where the 

 ground is softer, and attributes this difference solely to wear. His 

 figures (unfortunately mislabelled L. melanoleucus) may be matched 

 by specimens from the present series. While there may be some 

 truth in his contentions, the fact that both long and short billed 

 birds from the same locality are to be found in the present series 

 indicates that individual variation and, possibly, age, must be taken 

 into consideration as well as wear. Wliile it is true that hornbills 

 use their beaks for digging, this habit is not very extensive or very 

 frequently indulged in. As in most hornbills, the tail length is more 

 variable than that of the wing or the bill, and in this case it may 



FIG0RB 13." 



-The three outermost rectricks (right side op tail) op Lophoceros 

 erythrorhynchus krythrorhynchus to show variation 



well be that the ease and rapidity with which the long rectrices are 

 frayed and abraded are important factors. The color variations 

 are not particularly noticeable, the most variable feathers being the 

 outer remiges and the rectrices. The white marks on the primaries 

 vary from rather narrow transverse bars to almost circular spots. 

 In about half the specimens the next to the outermost primary has 

 no white on the outer web, while in the other 50 percent some (even 

 if only a very little) white is present on the edge of the outer web. 

 The outer three pairs of rectrices vary enormously with regard to 

 the disposition of white and dark. The five accompanying figures 

 are merely sample cases picked at random and could be multiplied 

 very easily. Neither sex nor age seems to be in any way correlated 

 with this variation. 



The size variations are presented in tabular form below. The series 

 is large enough to give a fair idea of the range of dimensional 

 variation in this bird. 



^ Proc. Zool. Soc. Lond., 1895, p. 498 : Dabulli, western Somaliland. 

 =«Kunj.'l. Sv. Vet. Akad. Handlgr., 1911, pp. 72-73. 



