86 LIFE-HISTORIES OF BIRDS 



web, and sometimes lack the complementary phalanges. 

 The tail has ten rectrices. In the humming birds, the ten- 

 uirostral type of bill prevails ; while in the other two groups, 

 the fissirostral, which was formerly supposed to relegate 

 them to the ffirundinidce. The breast-bone is broad, with 

 a deep keel which is either entire or doubly notched, poste- 

 riorly ; rarely, singly notched. The syrinx never possesses 

 more than a single pair of intrinsic muscles. 



2. C-Hcifli: contain about fifteen families, the great bulk 

 of the order. The sternum is ordinarily notched on the pos- 

 terior margin ; the muscles of the syrinx are mostly in pairs. 

 The feet are commonly small, and the toes vary remarkably 

 in their arrangement. TheCucuJidtc, the near relatives of 

 the Indicatorida or guide-birds of Africa, have the feet 

 permanently zygodactylc* by complete or partial reversion 

 of the fourth toe, the outer one being versatile. The AJce- 

 dinidce have the middle and outer toes completely coherent 

 for a considerable distance, representing the svndactyle or 

 anisodactylc type of foot. 



3. Pici\ comprehend three families, the lytigidiC of 

 Europe, Asia, and Africa ; the Picttmnida mainly Amer- 

 ican, and the Picidce or true Woodpeckers. The digits are 

 permanently paired, except in the two tridactyle genera. 

 The lower end of the metatarsus is modified, producing a 

 correspondence to the reverse position of the fourth toe ; and 

 the superior portion of this bone is perforated by canals for 

 the accommodation of the flexor tendons. The basal phal- 

 anges of the toes are short. The wing possesses ten prima- 

 ries with short coverts, which is exceptional in this order. 

 The tail has ten rectrices, which are soft and rounded in some 

 families of this group, but, which are stiff and pointed in the 

 Picidcc+ where a supplementary pair of spurious feathers 

 exists. In the lyngidcc, the nostrils are large and peculiarly 

 shaped ; while in the Picumnidtc and Pic/da* they are or- 

 dinarily covered with antrorse plumules. The bill is hard 

 and powerful, sharp or truncate ; the mandibles being equal. 



