152 ELEMENTS OF ORNITHOLOGY, 
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 acuminate. The tail of the Woodpecker shows such 
rectrices. A feather enlarged at the end (more or less like 
the beak of a Spoonbill) is 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 tail-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 ; it may 
be more, i.e. deeply forked, or it may even be extremely forked, 
which has been called forficate. 
There may be a median projection with lateral concavities at 
the tail’s hind margin. Then it is said to be a tail doubly emar- 
ginate or doubly forked. In the same way a tail which, instead 
of having an evenly rownded margin, has a median notch with a 
convex but rounded margin to the tail on either side of the 
notch, is said to be doubly rounded. If the tail ends with a 
simple, straight, transverse margin itis truncate, even, or square. 
There may be a pair of very long projecting ‘feathers, which 
are then said to be far-ewserted 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. 
