INTRODUCTION. 17 
of the snipe’s wing (Figure 52) illustrates this; the greatest distance which 
can be measured on this cut is the length of the wing. Second, length of tail 
or “tail.” This is practically the length of the longest tail feather, but since 
the tail feathers are embedded in the muscle and other tissues of the “ pope’s- 
nose” it is necessary to add a little to the actual visible length of the longest 
tail feather. Hence it is customary to feel for the root of the tail, place one 
leg of the compasses in the center of the pope’s-nose, and extend the other 
leg of the compasses to the end of the longest feather, the distance thus 
obtained being the length of the tail. Third, length of bill. Usually this 
means the same as length of culmen, the culmen being the profile or upper 
outline of the bill, and its length is obtained with the compasses by taking 
the distance in a straight line from the tip of the bill to the point where the 
ridge of the upper mandible meets the feathers of the forehead. This is really 
the chord of the culmen. In long-billed birds like snipe and sandpipers, 
which have little gape, this measurement is very nearly the same as the length 
of the bill, but in sparrows, hawks, swallows and a host of other birds, the 
measurement from the tip of the bill to the corner of the mouth would be very 
different from the length of culmen obtained as above Fourth, length of 
tarsus or simply “tarsus.” The tarsus of course is the shank, or what is 
loosely spoken of as the leg, and the measurement sought is the distance 
from the heel joint (wrongly called the knee) to the junction between the 
shank and the foot proper. This measurement should always be taken 
with the compasses and on the front of the shank, one point being placed at 
the junction between the upper leg, or tibia, and the shank, or tarsus, while 
the other point should reach the suture or crease which separates the shank 
from the root of the toes. When the legs are long and naked this measure- 
ment can be taken quickly and accurately ; if the legs are more or less feathered 
the measurement becomes somewhat less definite, but on the whole the length 
of tarsus is one of the most important data used in bird identification. Ref- 
erence to the various figures of bill, foot and wings, scattered through the 
text, will make still more clear the preceding directions. 
Of course other measurements are frequently called for, some of those 
in most general use being the length of the toes, either with or without the 
claws or nails, and it is probably safe to caution the beginner not to confound 
the toes with the claws. The claw or nail forms the terminal segment of each 
toe, and its length is of course a totally different thing from that of the entire 
toe. A bird’s foot as a rule has four toes and these are most often arranged 
with three pointing forward and one backward, the latter consequently 
being called the ‘hind toe.” It is also spoken of as the ‘‘first toe,’”’ while the 
front toes are numbered respectively 2, 3 and 4, number 2 being the inner 
toe, number 3 the middle toe and number 4 the outer toe. In most birds 
which run freely on the ground and seldom use the feet for grasping a perch 
or other object, the hind toe is apt to be somewhat elevated above the level 
of the front toes and it may be quite short or even entirely wanting. In some 
other birds two toes point forward and two backward, this arrangement 
being known as yoke-toed, and as a rule it is the outer or fourth toe which 
is turned backward, although there are cases in which the inner or second 
toe takes this position. 
The nomenclature of the wings, including the primaries, secondaries, 
tertiaries, greater, middle and lesser coverts, etc., etc., will be best learned 
by referring to Plate I and the various text figures. It should be noted, 
however, that the primaries are always nine or ten and are numbered from 
the tip or free border of the wing toward the body, number one being the 
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