12 
of the antennse and immediately in front of this crest is a distinct 
depression or fovea — the antennal fovea — which varies remarkably in 
different specie^, but is quite uniform within species limits. In some 
cases this fovea breaks through the frontal crest, uniting more or less 
completely with the ocellar basin, in which case the crest is said to be 
broken. The apex of the more or less prominent ridge between the 
bases of the antennae, in which this fovea is situated, is known as the 
antennal tubercle. 
The antenna- are always 9-jointed, the two short basal joints constitut- 
ing the scape and the others the llagellum. The antennae arc of great 
value in generic and specific characterizations, both in the matter of 
length relative to the body and 
in general shape and length of 
joints. They are usually simple 
and tapering, in some genera 
filiform, longer in the male than 
in the female, and frequentlyin 
the males with the basal joints 
of the llagellum more or less 
flattened or compressed. In 
some instances the basal joints, 
particularly in the males, are 
toothed or branched. 
The thorax, except in punc- 
tuation and hairy vestiture, 
presents few structural charac- 
ters of value in specific descrip- 
tion. It is important, however," 
to understand the terminology 
of the parts to properly appreciate the color descriptions. It presents 
a large number of sclerites — often small and somewhat obscure — which 
seem never to have been very carefully described, and some of (he 
more important divisions have been very commonly misapprehended. 
The accompanying illustration (fig. 3) shows more fully than will be 
undertaken in the text the superficial anatomical structure of this 
division of the body. When softened and subjected to dissection, the 
thorax readily separates into three parts — not, however, on the lines 
commonly supposed to represent the divisions between pro-, meso- and 
roetathorax. The pronotum attaches to the mesothorax and the so- 
called epistemum of the metathorax is seen to be mesothoracic. 
To the dorsal region of* the prothorax the pronotum, or first division 
of the thorax, is generally assigned. This sclerite, as just indicated, is 
most intimately and inseparably fused with the mesothorax and is 
scarcely at all attached to the lateral and ventral sclerites of the pro- 
thorax, which support the head and to which the anterior legs are 
joined. On this ground, Kirby refused to consider this sclerite protho- 
Pio. 2. — Month-parts of Paehynematus erichsonii: (A) a, 
labrum; &, clypeus; e, hypoclypeal plate ; d,d, anten- 
nal sockets; e, antennal fovea (B) Labium : a, men- 
tnm; 6, ligula; e, c, palpi. (C) Right mandible. il>> 
Left mandible. (K) Maxilla: a. cardo; b, stipes; c, 
galea; d, lacinia; <\ palpus (original). 
