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 iniddle 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. 13(i, 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 flabellae about a dozen in num- 

 ber. These flabellae may be cntireh' retracted so as to be invisible, 

 and are at intervals rapidly unfolded presenting a beautifully 

 symmetrical arrangement (Fig. 137). Buckton 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 atrial 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 cjdin- 

 drical, half a millimeter in diameter, transversely wrinkled and 

 bearing numerous, soft, concolorous, 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 



