468 PROCEEDINGS OF THE NATIONAL MUSEUIVI vol. no 



Tribe Euceratini 



Figure 41b 



Species of Euceros have been recorded mainly from Tenthredinoidea, 

 but E. jridigus Cresson has been recorded from Lepidoptera. 



Euceros thoracicus Cresson was examined. This species shows a 

 strong resemblance to many Ophioninae, Campoplegini, but the 

 mandibles also resemble those of the Scolobatini and the expansion 

 of the ventral part of the labial sclerite is also seen, although to a 

 lesser extent, in Opheltes. The small closing apparatus of the spiracle 

 is also seen in Opheltes. 



Tribe Pionini 



Figure 41c 



Rhorus clapini (Provancher) was examined. 



This is a somewhat isolated form, but the labial sclerite, although 

 very slender, does resemble that of most Mesoleiinae in being in- 

 complete ventrally. The type of mandible is also found, in a modified 

 form, in the Euryproctini and Mesoleiini. 



Rhorus mesoanthus (Gravenhorst) is figured by Beirne (1941). 



Tribe Mesoleiini 



Figures 42, 43 

 Larval Key 



1. With labial sclerite complete ventrally 2 



With labial sclerite very lightly sclerotized or unsclerotized ventrally .... 4 



2. Labral sclerite present *' Opheltes 



Protarchiis 22 

 Labral sclerite absent 3 



3. Six setae on prelabium Mesoleius 



Four setae on prelabium Lophyroplectus 



4. Posterior end of hypostoma with small expansion Hypsantyx 



Posterior end of hypostoma without small expansion Latnachus 



The broad ventral end of the hypostomal spm- figured in Lamachus 

 virginianus (Rohwer) appears to be present only in this species. 

 In other species of Lamachus the ventral end of the hypostomal spur 

 is slender. In most species of Lamachus examined the dorsal ends of 

 the labial sclerite had pronounced bubble-shaped projections similar 

 to those of Hypsantyx and the Euryproctini. 



The following have been examined: Opheltes glaucopterus jlavi- 

 pennis (Provancher) (fig. 42a), Mesoleius tarsilas (Cresson), M. 

 tenthredinis Morley (fig. 42b), Lamachus albopictus Cushman, L. 



" Opheltes differs from Profarchus in that the ventral part of the labial sclerite is less pointed. 

 M Of Beirne (1941). 



