l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



In Plafcros there is only one pair of labial muscles, the ventral 

 pair, -'/ ; they arise on the posterior ends of the anterior tentorial 

 arms and are inserted medially on the base of the prementum. The 

 levator muscle of the labial palpus, 24, is present. The rigid tentorial 

 structure that was found in Chauliognatkus is absent in Plateros. The 

 labral, cibarial, pharyngeal and hypopharyngeal muscles are all essen- 

 tially the same as in Chauliognatkus. 



Chauliognatkus pcunsylvanicus Deg., Cantharidae (figs. 65, 66, 

 67), and Phofuris sp., Lampyridae, are the larval forms considered. 



In Chauliognatkus (figs. 65, 66) muscle 5 does the same work as 

 the dorsal dilator muscle of the cibarimn, 5 (figs, i, 2), in the gen- 

 eralized form ; it is considered homologous though it is greatly 

 modified in origin and somewhat in its insertion. The other dorsal 

 dilator muscles of tke cibariuin, 6 and 7 (figs. 65, 67), form a com- 

 pact, linear group as do also the dorsal dilator muscles of tke pkaryn.v, 

 J I (fig. 67). There is a heavy tentorial modification present, but it 

 is less extensive than that of the adult ; it is also continuous with 

 the subpharyngeal plate. Hypopharyngeal bar }' (fig. 67) extends 

 posteriorly from the dorsal region of the structure. There is a 

 heavily sclerotized postoral subpharyngeal support that joins the head 

 on each side laterad of the mouth. The labial muscles are similar to 

 those of the adult and the posterior lateral sclerotized resilient bar, 

 KB (fig. 67), that was described in the adult form is also present in 

 the larvae. 



In Pkotnris sp. the musculature is similar to that of Chauliogna- 

 tkus; the muscles, however, are less well developed. 



XII. ELATEROIDEA 



Neotrickophorus carolinensis (Schfr.), Elateridae, and Chryso- 

 botkris fcmorata (Oliver), Buprestidae, are the adult forms from 

 this group used for study. 



In Neotrickopkorus (figs. 68, 69, 70) the full complement of labral 

 muscles is present. Upon first examination it was thought that only 

 the ventral muscle of the labriim, j (figs. 68, 70), was present, but 

 it was later determined that muscle j and the dorsal muscle of tke 

 labruui, 4, are so closely appressed as to appear as one. Muscle / is 

 inserted laterally on the posterior dorsal rim of the labrum while 

 muscle J is inserted ventrally and laterally as is the usual manner. 

 This is the only species in the order Colcoptera, examined in this 

 work, that exhibited any indication of an anterior (dorsal) labral 

 muscle. Another elaterid adult, Heteroderes nicholsi Notman, was 



