310 LIFE-HISTORIES OF BIRDS 



seldom naked inferiorly ; the tarsi frequently, and the toes 

 occasionally feathered ; but ordinarily both are naked, scutel- 

 late, reticulate, and often furnished with spurs. The bill is 

 generally short, stout, convex, and blunted, never cered or 

 largely membranous ; the basal part of the culmen contains 

 prominent antiae, which often fill the nasal fossae. The 

 head is often wholly or partially naked, and provided with 

 fleshy developments. The wings are abbreviated, strong, 

 and concave. The tail is completely absent in some genera, 

 and prodigiously developed in others ; the rectrices are 

 variable in number, but ordinarily limited to twelve. The 

 sternum generally exhibits an inordinate enlargement of the 

 posterior notches. The palate is schizognathoos, the diges- 

 tive system provided with an ample crop, the gizzard quite 

 muscular, the caeca capacious, and the inferior larynx 

 not furnished with intrinsic muscles. This order compre- 

 hends no less than seven exotic families, besides several 

 North American. In Eastern Pennsylvania, the single fam- 

 ily Tctraonidce, containing two sub-families, is represented. 



Family Tetraonid.80. Grouse, etc. 



The above term is commonly restricted to the Tetra- 

 onidce, or True Grouse ; the partridges being thrown into 

 another family which embraces several sub-families. But 

 they are so variously interrelated, that Dr. Coues has em- 

 braced them in one family. 



Subfamily Tetraonin8B. Grouse. 



The birds of this group have the head completely feath- 

 ered, except a naked strip of skin above the eye. The 

 nasal fossas are thickly feathered. The tarsi are completely 

 feathered to a greater or less extent ; the feathers sometimes 

 extending on the toes to the claws. When naked, the toes 

 are furnished with fringe-like processes. The tail varies, but 

 is never folded, and composed of 16-20 feathers. The 



