150 PICIDA3, OR THE WOODPECKERS. 
typical indeed tlian others, a variation which is 
highly interesting, since it is by such aberrant spe- 
cies, — which writers are continually mistaking for 
subgenera, — that the gradations in the chain of be- 
ing and the union of different forms of structure are 
effected.' Without these, in short, the progressive 
developement of a change in structure could not be 
accomplished. 
BLACK-BODIED WOODPECKER. 
Hemicircus rubigimsus, Swains. 
Above chestnut-rod ; beneath blackish brown ; head brown ; 
spot on each side the nape, crimson ; bill yellowish ; tail 
very short. 
The only specimen we have ever seen of this ex- 
ceedingly rare species was purchased with a number 
of other skins, all of which were from "Western 
Africa. We therefore conclude this was from the 
same locality, although its geographic habitat does 
not rest on the same sure foundation as that of the 
majority of birds described in these volumes. 
The size is superior to that of the Picus Capcnsis 
of authors ( Dendrolates Capensis J, but the extreme 
shortness of the tail brings it only to the same 
length as that bird ; this peculiarity likewise dis- 
tinguishes the Dendrolates f ulviscapus , or the little 
gold-winged woodpecker of the Cape, with which, 
