86 
The Ohio Naturalist. 
[Vol. XIII, No. 5, 
The antennae (Fig. 138, a) are located close above the buccal 
cavity and seem to consist of a basal fleshy segment and two, 
slightly-elongated pieces side by side at the apex. These are 
located on a fleshy, partly bifurcated process of the head seg¬ 
ment. The small pieces at the tip are not alike in appearance; the 
one nearer the middle line is abruptly constricted near its middle, 
beyond which it continues with less than a fourth its diameter at 
the basal half. The outer one is of nearly equal diameter to the 
truncate apex. 
The integument as a whole is provided with short, flexible, 
light-colored hairs (Fig. 130, b ), which are specialized on the pro¬ 
legs, on the posterior breathing appendage, and also into the 
segmental hairs. 
The anterior spiracles (Figs. 131, b; 132), are borne on a pair 
of horn-like prominences which are capable of considerable exten¬ 
sion but are usually rather closely retracted. The tip is marked 
by a sub-circular opening guarded by twenty rounded lobes. 
The pro-legs, of which there are seven pairs, are simply ven¬ 
tral, knob-like projections of the body surface, over which the 
ordinary integumental vestiture has become specialized (Fig. 
138, c). The hairs are larger, heavier, and decidedly curved and 
retrorse; there are several sizes of these hooks on each pro-leg. 
They are very efficient organs of locomotion in soft mud or over 
hard surfaces, and in the present case doubtless enable the larva 
to migrate to the place of pupation as described below. 
The anal opening is located ventrally near the base of the 
“tail.” It is slit-like, and is very peculiar in that it opens among a 
group of soft, retractile, radiating flabellas about a dozen in num¬ 
ber. These flabellce may be entirely retracted so as to be invisible, 
and are at intervals rapidly unfolded presenting a beautifully 
symmetrical arrangement (Fig. 137). Buekton suggests that 
they may have a renal function. 
The posterior respiratory appendage (Fig. 131, d) is a most 
remarkable and highly specialized organ which enables the larva 
to feed at various depths beneath the water without coming to the 
surface for its serial respiration. The spiracles are situated dis- 
tally on an elongated tube-like appendage, which is extensile and 
retractile in a telescopic manner. It is composed of three sections 
of different caliber and superficial appearance, each double in 
nature, enclosing two tracheae, but fused medially to the tip, 
never forked. These sections are capable of sliding one within 
the other. The one next the body is the largest, nearly cylin¬ 
drical, half a millimeter in diameter, transversely wrinkled and 
bearing numerous, soft, eoneolorous, blunt hairs, similar to those 
of the body surface (the integumental hairs ) but only about half 
as large (Fig. 134). The middle segment of the posterior appen¬ 
dage is about two-thirds the diameter of the basal one, and is 
