TARSAL STRUCTURES 63 
The front tibiee are often the longest in the Sabethini. At their apices the tibiee 
are more or less excavate behind and bear several stout spines, and in addition, 
particularly on the front and hind pair, numerous stiff sete. Upon the front 
and hind tibiz these sete are densely massed upon the broader portions of the 
tibiz and in addition there is, subapically on the inner side, a transverse row of 
very densely placed sete. Below this row of sete are usually present several 
slender spines, also in a transverse row. These spines have been termed the 
tibial scraper and their presence or absence, on the hind tibie, and their number, 
are of systematic value. The tibiz also bear longitudinal series of spines and 
these differ in character with the species. 
The tarsi are slender, cylindrical and differ considerably in their proportions 
on the three pairs of legs. They are, as a whole, much longer on the hind legs 
and it is they largely that determine the predominating length of this pair of 
legs. The first tarsal joint is always very long in all three pairs of legs, although 
usually somewhat shorter than the tibia. In Anopheles, however, the first tarsal 
joint of the hind legs is longer than the tibia. The first tarsal joint is by many 
systematists called the “ metatarsus.” The application of this term is incorrect 
as it implies something beyond, or outward, from the tarsus. As the first tarsals 
differ from the following ones only in length, and this is not true of all Diptera, 
there is no reason why they should be designated by a special term. Further- 
more the introduction of this term has brought about much confusion in de- 
scriptive work; when an author has been inconsistent in this usage it is some- 
times impossible to determine if his “ first joint” is in reality the first or the 
second. 
Each tarsal joint is shorter than the one preceding it; the only interruption 
occurs, sometimes, in the last two tarsals of the front and middle legs, the fourth 
joint being in such case the shorter. This progressive reduction is most rapid 
on the front and middle legs, the hind tarsi are always much the longest. In 
many forms the front tarsi are, as a whole, noticeably shorter than the middle 
ones, while still more often they are nearly equal. In some Sabethini the middle 
tarsi are shorter than the anterior ones. 
The fourth tarsal joint, as already indicated, is often shorter than the fifth, 
either upon both the front and middle legs or upon the front legs alone. This 
difference is greatest in those males in which the claws show the most sexual 
modification. In the female the fourth joint, if shorter than the fifth, is usually 
but slightly so; in Bancroftia, however, the fourth joint is very short, about as 
long as broad. In the females of Anopheles and in both sexes of most Sabethini 
the last tarsal joint is distinctly the shortest. All the tarsal joints but the last 
bear a pair of spurs apically beneath. In addition there are longitudinal series 
of spines or sete; these, and the terminal spurs, are variously developed in the 
different genera and species. The last tarsal joint bears the two claws, or, in a 
few cases, a single claw. In the females, and in many males, the fifth tarsal 
joint is cylindrical, resembling in character the other joints. It is often ob- 
liquely excised at the tip beneath for the insertion of the claws and their mechan- 
ism. In the males of most Culicini, and in the male of Joblotia, the fifth tarsal 
