TABANIDA OF OHIO. IL 
nent, the proximal joint projects forward so that the large distal 
segment is carried before all the other mouth parts. 
The rear of the head is usually referred to simply as the 
occiput, near the middle of which the head is joined to the thorax, 
a narrow strip lying above this junction is sometimes referred 
to as the nape or cervix. The cervix in this species is quite ob- 
viously bounded by sutures. 
Head of male. The head is larger and approaches nearer 
to hemispherical than in the female. The eyes are continuous 
for a long distance and thus the front is divided into two parts 
called the vertical and frontal triangles. The former is very 
small and is bounded above by the vertical margin and bears no 
ocelli or simple eyes in this species. The latter is limited below 
by the antennz and includes the subcallus. Because of the in- 
creased size of the head the antennz appear to have their union 
higher up. 
The face in this sex is different than in the female. The sides 
or cheeks are about in the same plane with the surface of the eyes 
while the median part is much depressed. The mouth parts also 
differ ; the mandibles are entirely lacking and some of the other 
parts are noticeably reduced. The second joint of the maxillary 
palp is smaller and shorter than in the female, and turns upward 
to lie against the face. The uppermost greenish band of the eye 
is abbreviated outwardly and just above it, next the frontal tri- 
angle, is the division between the lower area of small facets and 
the upper area of large facets of which the eye is composed. On 
the outer and upper margin of the eye the area of small facets 
is extended to where the eye meets the verticle triangle. 
Thorax. The three primary divisions of the thorax are not 
easily separated, but the 2esothorax comprises nearly all the space 
visible from above, including the posterior, somewhat triangular 
portion called the scutellum. 
The prothorax is small but is easily located from the fact 
that it bears the anterior pair of legs.. A small lobe of the pro- 
thorax, easily distinguished by being lighter in color, is closely 
applied to each anterior corner, or humerus of the mesothorax,. 
Lying between the attachment of the anterior leg and the hume- 
rus are two small prominences and just posterior to these lat- 
ter is the anterior thoracic spiracle which marks the beginning 
of a suture, the dorso-pleural suture, which passes backward 
through the attachment of the wings, and ends beneath the front 
edge of the scutellum. 
The dorso-pleural suture marks the division between the 
superior and lateral parts of the mesothorax, known respectively 
