PICID.E. 



301 



Analogies. 



CONIROSTRES. 



) Picus, Lin. 



Dentirostres. 



scansores. 

 Tenuirostres. 



FlSSIROSTRES. 



PICUS. 



1. Typical group. 



Sub-genera, 

 Bill most perfectly wedge-shaped, 



the angles equal ; neck length- 

 ened, slender ; tarsus mani- 

 festly shorter than the outer 

 posterior toe ; occiput with a 

 rigid pointed crest. 



2. Sub-typical group 



Bill depressed, imperfectly wedge- 

 shaped, lateral ridges nearest 

 the culmen ; neck less slender ; 

 outer posterior toe shorter than 

 the anterior. 



3. Aberrant group. 



Lateral ridges of the upper man- ' 

 dible close to the margin of the 

 bill j tarsi of equal length with 



Typical Species. 



Picus principalis, L. 



■Dryotomus, Sw. Picus martius, L. 



Denbrobates, Sw. 

 ■■Apternus, Sw. 



the outer posterior toe. 



Picus affinis, Sw. 

 Picus tridactylus, L. 



. Dendrocopus* , Koch. Picus pubescens,L. 



On the two typical forms we need not dilate ; but the aberrant group requires 

 a more particular explanation. As a whole, it still retains two of the most 

 important characters of the genus, — the perfectly acute bill and straight culmen ; 

 and secondly, the lengthened posterior outer toe. It is obvious that both these 

 are pre-eminently typical distinctions ; since the first implies a greater facility 

 in breaking, and the latter a firmer support in climbing, than is found in any 

 other group of the true Woodpeckers beyond the circle of this genus. But, on 

 the other hand, we detect a considerable diminution of strength in the unequal 

 angles of the bill, in the greater length and slenderness of the tarsus, and more 

 particularly in the neck, which is not of that peculiar length and compactness so 

 conspicuous in the typical structure, and which implies some particular internal 

 arrangement of the muscles, belonging almost exclusively to such powerful 

 birds as P. principalis, robustus, &c. We need not, therefore, look for further 

 distinctions, to detach the typical from the aberrant forms ; but as it is important 

 that these latter should be further analyzed, we shall now give their natural 

 characters more in detail. 



* Cited by Wagler, Sp. Avium. 



