IS4> ON THE CLASStPICATION OF BIRDS. 
cular attention ; we only regret that our confined limits 
prevent us from giving more than an abstract of their 
internal relations. 
(150.) The true woodpeckers (^Picianm Swains.) are 
typically represented by the great ivory-bitted species 
already noticed. Here the upper and the lower ridge 
of the biU exactly correspond in their inclination to- 
wards the tip, rendering the bill a perfectly straight 
wedge. This construction is rendered still more perfect 
by a ridge, forming a strongly carinated line, which 
runs parallel to the culinen, and is situated nearly half 
way between that and the external margin of the upper 
mandible. The crests of these birds are very short, 
rigid, and turned upwards : but their chief distinction, 
as a genus, rests on the structure of the feet, the hinder 
external toe being manifestly longer than that in front : 
this peculiarity is even extended to such aberrant spe- 
cies as have one of the small toes wanting, as the two 
northern species, Apternus tridar.tylus and areticus. 
To this group, therefore, we restrict the generic name 
of Ficus, and it includes all the British species ex- 
cepting viridis. In the next group, Chrysoptilus, we 
find a diminution of these typical excellences ; the bill, 
as in our common green woodpecker, is still nearly 
straight, but the lateral ridge, before alluded to, is 
placed close to the culmen, and the hind toe is either 
of equal length or slightly shorter than the fore toe : 
the crest, although stiU short, is less rigid, and not so 
much developed. The colours of these birds arc always 
gay ; green, and not black, predominates ; and most of 
the typical species have the quills of a beautiful golden 
hue, — a circumstance which svqg'ests the generic name 
of Chrysoptilus. The third is a highly elegant genus : 
the bill is now no longer straight ; the culmen, or upper 
ridge, being evidently more arched than the lower 
ridge, or gonys ; and this latter is particularly short, 
owing to the prolonged advancement of the chin, 
which occupies full one half of the under mandible. 
The lateral ridge of the upper mandible is as in 'tlie last 
