SCALES OF THORAX 73 
typical Culex. In Aédes squamiger and some other species the scales of the 
upper series are broad and subtruncate and these are the “ fan-shaped ” scales 
of Theobald. While in most species of A édes the color of all the scales is dark, in 
certain species there is a sprinkling of light-colored scales. This is also the case 
with certain species of Psorophora, and in some species the scales are grouped 
to form a definite pattern (P. discolor, P. signipennis). 
In the genus Mansonia the scales of one series are more or less broadened with 
a tendency to oblique truncation. This is the least marked in Mansonia fascio- 
latus of any of the species we have examined and in it many of the scales are 
hardly different from the “ fan-shaped” ones above mentioned. These are the 
so-called “'Taniorhynchus scales” of Theobald. In Mansonia titillans these 
scales are differentiated most and very broad and asymmetrical and many of 
them are shallowly emarginate at their apices. This constitutes the “ Mansonia 
scales” of Theobald. A similar type of scales, but with more rounded apices, 
occurs in Bancroftia fascipes. Hardly distinguishable in character are the wing- 
scales of Aédeomyia squamipennis, designated as “ Aédeomyia scales ” by Theo- 
bald; their angles are somewhat more rounded. 
Along the costal margin there is often a series of scales which are combined 
into groups of several in such a way that they give the effect of stout spines and 
this has led to the introduction of the term “spinose.” The spinose effect is 
produced by the crowding together of the pointed apices of several scales. Fre- 
quently this spinose arrangement is hidden by overlapping broader scales. 
The head behind the eyes is covered with scales. The covering may be en- 
tirely of broad scales lying flat, as in Megarhinus, or there may be several types 
of scales present. Very often there is an area of greater or less extent on the 
vertex covered with “ narrow, curved scales.” In addition there is frequently 
a mass of “upright forked scales” upon the vertex. These are narrow scales 
with a long slender stem and expanded fan-like apically; the apical margin is 
roughly spinose, or it may be emarginate or tridentate. Transition forms may 
occur between these and the other scales. Usually these “upright forked 
scales” are in a dense mass on the vertex. In Joblotia and Lesticocampa they 
are arranged in a long, regular, transverse row on the occiput. When the pro- 
thoracic lobes are large the upright forked scales are absent. 
The thorax is more or less clothed with scales. This scale covering is least 
developed in the lowest forms, the Anophelines. In these there is but a sparse 
vestiture of hair-like scales upon the mesonotum, so that the integument itself 
remains plainly visible. When the scale-covering is sparse the integument 
usually shows peculiarities of coloration and it may be ornamented with spots, as 
in many Anopheles and Aédes fulvus. The prothoracic lobes are usually more 
or less scaled. There may be but a few loose scales or the lobes may be densely 
covered with them. This latter condition is particularly true of the Sabethini 
and other forms with large prothoracic lobes and the coloration of this vestiture 
is often important for specific determination. The mesonotum is usually for 
the most part densely covered with scales. In many forms a median depression 
in front of the scutellum, the ante-scutellar space, is devoid of scales. The 
