PICID.E — THE WOODPECKERS. 493 



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much curved to the acutely pointed (not truncate) tip. The commissure 

 considerably curved. Bill without any ridges. The nostrils liroadly 

 oval, and much exposed. Anterior outer toe longest. 



The preceding diagnoses will serve to distinguish the three groups suf- 

 ficiently for our present purposes ; tlie bill being strongest in the ricuuv and 

 best fitted for cutting into trees by its more perfect wedge-shape, witli 

 strengtliening ridges, as well as by the lateral bevelling of both mandibles, 

 which are nearly et[ual in thickness at the base, and with their (jutlincs 

 nearly straight. The lateral ridge is prominent, extending to the edge or 

 end of the bill, and overhangs the nostrils, which are narrow and hidden. 

 The Centurece and the Colaptccc have the upper mandible more curved 

 (the commissure likewise), the lower mandible smaller and weaker, the 

 bill with little or no lateral bevelling. The nostrils are broadly oval and 

 exposed. In the former, however, there is a distinct lateral ridge visible 

 for a short distance from the base of the bill ; while in the other there 

 is no ridge at all, and the mandible is greatly curved. 



In all the species of North American Woodpeckers, there is more or less 

 red on the head in the male, and frequently in the female. The eggs of all 

 are lustrous polished white, w^ithout any markings, and laid in hollow trees, 

 upon a bed of cliips, no material being carried in for the construction of the 

 nest. 



Section PICE^. 



With the common characters, as already given, there are several well- 

 marked generic groups in tliis section of Woodpeckers which may be arranged 

 for the United States species as follows : — 



A* Posterior outer toe longer than the anterior outer one. (Fourth toe longer 

 than third.) 



a. Lateral ridge starting above the middle of the base of the bill, and 



extending to the tip. 



1. Campephilus. Lateral ridge above the middle of the lateral profile 

 of the bill when opposite the end of the nostrils, which are ovate, and 

 rounded anteriorly. Bill much depressed, very long ; gonys very long. 

 Posterior outer toe considerably longer than the anterior. Primaries 

 long, attenuated towards the tip. Spurious quill nearly half the second. 

 Shafts of four middle tail-feathers remarkably stout, of equal size, and 

 abruptly very much larger than the others ; two middle tail-feathers 

 narrower towards bases than towards end.* A pointed occipital crest. 



2. Picus. Lateral ridge in the middle of the lateral profile opposite the 

 end of the nostrils, whi<'h are ovate and sharp-pointed anteriorly. Bill 

 moderate, nearly as broad as high. 



^ A character common to all the members of the genus, and distinguishing them from the 

 .s))eci;*s of evevy other ; this |)eeuliar form of the middle tail-feathers is caused principally by a 

 folding of the webs downwai d. ahno-t against each other. The under surfaces of the shafts have 

 a very deep groove their whole length, which is seen in no other gemis. 



