26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



10 (figs. Ill, 112), is branched; the anterior branch loA arises 

 laterally in the anterior frontal area on the posterior surface of the 

 epistomal suture. The labial muscles are strong, especially the dorsal 

 muscle of the labium, 20 (figs. 112, 113). There is an unusual ten- 

 donous structure (fig. 112, TS) that arises broadly, medially and 

 basally from the ventral labial wall ; it extends anteriorly to be 

 inserted medially on the dorsal wall of the labium in the anterior 

 region. A contraction of the dorsal labial muscle, 20 (fig. 112), 

 would exert a pull on the labium at the point of insertion ; this tendon 

 that joins the anterior dorsal labial surface with that of the posterior 

 ventral region probably retracts the anterior labial area when muscle 

 20 contracts. There is a strongly sclerotized intralabial brace, IR 

 (fig. 112), in the posterior region of the labium that terminates 

 laterally in the integument. 



In Donacia the compressor muscle of the labrum, i, is absent ; 

 the anterior branch of the muscle of hypopharyngeal bar Y, loA, 

 arises as it does in Leptinotarsa. The cibarial, pharyngeal, hypo- 

 pharyngeal, labral, and labial muscles are apparently homologous with 

 those found in Leptinotarsa. 



In Galeriicella the compressor muscle of the labrum, i, is absent; 

 the anterior branch of the muscle of hypopharyngeal bar Y, loA, 

 arises as it does in Leptinotarsa. The cibarial, pharyngeal, and labial 

 muscles are homologous with those found in Leptinotarsa. 



For the larvae in this superfamily Leptinotarsa decimlineata (Say) 

 and Typophorus viridicyaneus (Cr.), Chrysomelidae, were selected 

 for study. 



In Leptinotarsa (figs. 114, 115, 116) the muscles are very well 

 developed. The compressor muscle of the labrum, i (figs. 114, 115), 

 is present; the cibarial muscles, 6 and y, and pharyngeal muscles, 11 

 (fig. 114), are long because of the space between the dorsal wall of 

 the stomodaeum and the head wall. The muscle of the hypopharyngeal 

 bar Y, 10 (fig. 114), is subdivided into many units. The ventral dila- 

 tor muscle of the pharynx, jo (fig. 114), is especially massive; the 

 dorsal and ventral labial muscles, 20 and 21 (figs. 114, 116), and 

 the muscle of the prementum, 22 (figs. 114, 116), are all strong. 

 The latter muscle is inserted on the ventral wall of the labium on an 

 area in which the division of the prementum is indistinct ; the dorsal 

 and ventral labial muscles, 20 and 21, are inserted on the base of 

 prementum i (fig. 116). The muscle of the prementum, 22 (fig. 

 116), is inserted on the base of the second division of the prementum, 

 though the dividing suture is indistinct. 



The musculature in Typophorus is similar to that of Leptinotarsa 

 except that the compressor muscle of the labrum, i, is absent. 



