152 ELEMENTS OF OENITHOLOGY. 



feathers may be of very different shapes in different species of 

 birds. When very narrow they are said to be linear, and when 

 very long and slender they are called filamentous. Each is 

 termed lanceolate when tapering to the tip from a broader base. 

 When the feather becomes gradually very pointed it is called 

 acute ; but if it is suddenly narrowed towards the point it is 

 termed acvmindte. The tail of the Woodpecker shows such 

 rectrices. A feather enlarged at the end (more or less like 

 the beak of a Spoonbill) ig called spatulate. A mucronate or 

 spinose rectrix is one in which the rachis projects at its end 

 beyond the vanes. This condition is also sometimes spoken of 

 as spinose. A truncate rectrix is one seeming to be cut straight 

 off transversely at its end, while if its terminal border is con- 

 cave, it is said to be incised. 



A very fine and curiously developed tail is that of the Lyre- 

 bird, most of the tail-feathers of which creature have their 

 barbs widely separated, so that the webs are quite loose. 

 The true tail-feathers may be very short, as in the Tinamou ; 

 or quite rudimentary or downy, as in the Grebe. 



To estimate the shape of the taU-feathers, they should 

 be nearly closed. Then the posterior margin of the whole 

 group of rectrices may or may not appear concave, when the tail 

 is more or less forked. If this forking is only minute, the tail 

 is said to be emarginate. If truly forked it is furcate j it may 

 be more, i.e. deeply forked, or it may even be extremely forked, 

 which has been called /ory?ca<«. 



There may be a median projection with lateral concavities at 

 the tail's hind margin. Then it is said to be a tail doMy emar- 

 ginate or doubly forked. In the same way a tail which, instead 

 of having an evenly rounded margin, has a median notch with a 

 convex but rounded margin to the tail on eithfer side of the 

 notch, is said to be doubly rounded. If the tail ends with a 

 simple, straight, transverse margin it is truncate, even, or square. 

 There may be a pair of very long projecting feathers, which 

 are then said to be far-exserted or " produced." If the rectrices 

 shorten gradually and successively from within outwards, the ' 

 tail is said to be graduated. If they thus shorten less and less, 

 they form a cuneate or wedge-shaped tail, and this may become 

 acutely cuneate or acute. 



The tail-feathers may fold up so as to form a whole, convex 

 above or, on the contrary, a convex below, so as to somewhat 

 simulate the shape of a boat. 



