THE CANADIAN ENTOMOLOGIST. 255 



apparently with a good-sized cavity within. Spiracles of other Chryso- 

 melid larvae have merely two lips or flaps, guarded inside by a few hairs. 

 At the base of each of the sickle-like appendages occurs the eighth ab- 

 dominal spiracle, which 1 believe to be open. The openmg can be seen 

 very clearly in one mount, though it occurs considerably below the 

 surface of the body, and would probably not be seen except in a 

 prepared specimen. A trachea branching from the main trunk can 

 easily be seen opening at each of these spiracles. Around each of 

 these and forming the base of the appendage is a circular, chitinous 

 structure, apparently tubular. From this arises the appendage with no 

 visible line of demarcation. 



In cross section each appendage is seen to consist of five passage- 

 ways. The lower side of the appendage is membranous and encloses the 

 lower channel which extends up through the central portion, between the 

 two main canals. This membrane is clearly an outgrowth of the outer 

 cuticle, connecting the chitinous wall of the two lateral channels, and 

 doubtless covering the whole appendage, though not discernible in a 

 rough, thick section. The two lateral passages have thick, chitinous 

 walls, marked with striations, seemingly tracheal tjeindia. The two 

 upper passages are open above, but can be readily closed by a wedge- 

 shaped piece which runs along the top of the appendage. The lower 

 canal has absolutely no connection with the tracheal system, as far as I 

 can observe, and the membrane enclosing it below is continuous with 

 that of the cuticle of the eighth segment. The lateral passages open into 

 the tube surrounding the spiracle. At their base this is at first striated 

 as are the passages, but the striations become irregular, forming a net- 

 work, and finally a sieve-like or grate-like structure on the anterior por- 

 tion. When the appendage is viewed laterally it is transparent enough to 

 reveal a series of elliptical openings running along the upper portion, two 

 series evidently arising from each of the lateral passages. From each of 

 these openings arise several small tubes, sometimes branching slightly 

 near the base, each of these structures resembling a rather coarse minia- 

 ture gill. By breaking open a lateral passage from below one or two of 

 these holes can be clearly seen. The outer series of holes and the tubules 

 branching from each are easily seen both by a lateral view and cross sec- 

 tion. The exact structure and position of the inner series I have not 

 been able to determine so satisfactorily, but they seem to extend along 

 the membrane forming the side of the wedge-shaped apex of the append- 



