254 THE CANADIAN ENTOMOLOGIST. 



States that in cross section each is seen to be composed of five canals, two 

 pairs above and a single larger passage below, which opens below slightly 

 before the tip. By inserting the appendages into the roots the larvse are 

 enabled to draw in the air found in the large vascular bundles, through 

 this opening in this lower channel, which supposedly connects with the 

 tracheal system. Concerning the two upper pairs of canals he says 

 nothing except that they are highly chitinized to secure the firmness ot 

 the appendage, but concerning the lower, remarks : " How this formation 

 — a chitinous tube opening at the end — came to pass histologically I was 

 not able to ascertain till the present observations. It comes near calling 

 to mind a tubular outgrowth of the hypodermis at the stigma. In 

 accordance with this is the fact that the wall of this questionable canal, 

 especially near to the base of the appendage, is not simple, but is double, 

 and no cells are to be found between.' (Free translation.) In support 

 of this view he found that small pairs of scars which when cross-sectioned 

 exactly correspond in size to the tips of the appendages, and are at the 

 correct distance from the scars where the larva had been feeding, could 

 be readily found, and these I have found on stems bearing the cocoons of 

 D. piscatrix. Doctor Schmidt-Schwedt states, however, that in removing 

 the roots of the food plant from the mud the larvae always released their 

 hold, and that when rearing them he did not find them with the 

 appendages inserted until he darkened the breeding cage, and then that 

 ikio. points were found inserted, but that they were disturbed by the light 

 and withdrew them in a short time. Perris states that he cut off these 

 appendages at the base without injuring the larva. But as Dr. Schmidt- 

 Schwedt says, he did not state how long they would live under water with 

 them removed. On the other hand, neither does the latter writer state 

 that he determined whether or no the larva would not live under water if 

 entirely removed from the root. 



I have not been able to study any live larva^ to determine the func- 

 tion and manner of use of these interesting appendages, though I hope to 

 do so at an early date, but have made a very careful study of their struc- 

 ture, only, however, by means of free-hand sections. First, however, it may 

 be noted that true spiracles occur on the cephalo-lateral angle of the 

 mesa-thorax and upon the first seven abdominal segments, as in other 

 Chrysomelid larvae. The structure of the spiracles, however, is rather 

 different from any others I have observed. I have not made any sections 

 of them, but a lateral view is figured, showing them to be elongate and 



