40 



FORMS OF TAILS THE FEET. 



some flycatchoivs, most of the terns, etc., etc. It would ))e advisable to have 

 a term to express such extreme condition, which I shall call forficate, when 

 the depth of the fork is equal to, or greater than, the length of the shortest 

 (middle) pair of feathers ; it occurs among our birds in the genera Milvulus 

 (no. 104), Sterna (291), and elsewhere. Double-iov\i.Q.>\ or cZozt^/e-rounded 

 tails are not uucomniou ; they result from combination of both gradation 

 and forking, in this way: — Let the middle feathers remain constant, and 

 the next two or three pairs progressively increase in length, then the rest 

 successively decrease ; evidently, the tail is forked centrally, gradated exter- 

 nally : this is the double rounded form; it is shown in the genera Mijiadeales 

 (no. 52) and Anous (294). N^o-sv with middle feathers as before, let the 

 next pair or two decrease in length, and the rest progressively increase to 

 the outermost : then we have the double-forked, a common shape among 

 sandpipers. In the latter case, the forking rarely amounts to more than 

 simple emargination, and generally is really little more than simple protru- 

 sion of the middle pair of recti'ices in an otherwise slightly forked tail ; and 

 in neither case is the gradation either way often great. 



Various shapes of tails, which the student will readily name from the 

 foregoing paragraph, are illustrated in tigs. 17, 19, 29, 30, 32, 54, 57, 68, 

 73, 76, 84, 98, 106, 117, 120, 121, 126, 133, 135, 137, 144, 145, 147-52, 

 177, 206, 214. I should also allude to the folded tail of the barn-yard fowl 

 {Gcdhm bankivl, var.) a very familiar but rare form. One of the most 

 beautiful and wonderful of all the shapes of the tail is illustrated by the 

 male of the famous lyre-bird (Menura stijyerba), shown in the figure at the 

 end of this Introduction. 



It should be remembered that to determine the shape, the tail should be 

 viewed neuiii/ closed ; for spreading will obviously make a square tail round, 

 an eniarginate one square, etc. I append a diagram of the principal forms. 



Fig. 7, — Diagram of shapes of tair 



Fi«. 7. cuh, rounded ; aec, gradate ; aic, cuneate-gradate ; ale' cuueate ; abc, double- 

 rounded; feg, square; fliij, emargiuate ; fneog, double-emargiuate ; Jciiii, forked; kem, deeply- 

 forked; kbm, forficate. 



The Feet. 



§ 71. In ALL BiiiDS, the posterior extremities are organized for progres- 

 sion ; for walking, hopping, or running on land, in all; but a few of the 



