134 ON THE CLASSIFICATION OF ‘BIRDS. ne 
cular attention ; we only regret that our confined limi 
prevent us from giving more than an abstract of thei 
internal relations. 
(150.) The true woodpeckers (Piciane Swains.) ar | 
typically represented by the great ivory-bitted species 
already noticed. Here the upper and the lower ridge 
of the bill exactly correspond in their inclination to- 
wards ‘the tip, rendering the bill a perfectly straight 
wedge. This construction is rendered still more perfec 
by a ridge, forming a strongly carinated line, which 
runs parallel to the culmen, and is situated nearly half 
way between that and the external margin of the upper 
mandible. The crests of these birds are very coll 
rigid, and turned upwards: but their chief distinctio 
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 tridactylus and arcticus. | 
To this group, therefore, we restrict the generic name 
of Picus, 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 still short, is less rigid, and not so } 
much developed. The colours of these birds are always | 
say; green, and not black, predominates ; and most of 
the typical species have the quills of a beautiful golden 
hue, —a circumstance which suggests 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 low 
ridge, or gonys ; and this latter is particularly shor 
owing to the prolonged advancement of the chit 
which occupies full one half of the under mandible. 
The lateral ridge of the upper mandible is as in the we 
if 
t. 
