26 ENTOMOLOGICAL SOCIETY 



thorax, tubercles I to VI are grown together and form the cervical 

 shield ; VII and VII [ are sometimes distinct and sometimes 

 grown together ; IX and X are as on the other thoracic segments ; 

 XIII and XIV are usually grown together, forming a chitinized 

 sternum which is cleft on the caudal margin. The tubercles 

 are diagrammed as seen from the dorsal and ventral aspects, as 

 most of the larvae are naturally flattened. In studying them, 

 when sufficient material was available, I have mounted the skins 

 in Canada balsam. 



The thoracic spiracle is always surrounded by or just above 

 mesathoracic tubercle VII. The abdominal spiracles are situated 

 either between or laterad of tubercles V and VI. Spiracles are 

 always found on the first seven abdominal segments in the usual 

 position. In theHispidae they are lacking on the eighth, but very 

 large, round spiracles are found dorsally on the ninth segment. 

 In Donacia the spiracles of the eighth segment are much en 

 larged, are close together near the dorso-meson, and their bases 

 are prolonged into long sickle-shaped horns which aid in respira 

 tion. 



In some larvae the eighth abdominal spiracles are wanting. 

 Just below the spiracles, at a variable distance from them, branch 

 off from the trachea leading to the spiracle, two short tracheal 

 appendages, which end blindly, merely forming small pockets or 

 sacs. They are peculiar structures found in almost all of the 

 larvae examined, whose structure I fail to ;,nderstand. 



The legs are usually short and thick. In one genus of the 

 Hispidae, Octotoma, they are wanting. The segments seem to 

 be homologous with those of the beetle. The coxal segment is 

 much the largest, and is usually closely appressed to the body. 

 On the outer side it is slightly articulated with a well chitinized 

 tubercle which I have numbered IX, and which seems to be con 

 siderably like the trochantin described by Walton. The trochan- 

 ter is triangular, and the femur and tibia are more or less rectan 

 gular in profile. The tarsus is short, somtimes hardly visible. It 

 bears a single claw, and in the Gallerucini a well developed em- 

 podium or pulvillus. Such is a brief outline of the characters of 

 the larvae of the Chrysomelidae in the broadest sense. 



In their classification of the Chrysomelidaa, Leconte and Horn* 

 divide it into eleven tribes, grouping them together as shown on 

 the chart. The larval types of these different tribes are easily 

 recognized, though their relationships appear somewhat different 

 from those of the adults. 



The larvae of the Donaciini feed upon the roots of aquatic plants, 

 are cylindrical, slightly arcuate, tapering slightly cephalad from 

 the sixth or seventh abdominal segment, and sharply caudad ; 



(*Vide, p. 336, LeConte and Horn, Classification of the Coleoptera.) 



