THE CANADIAN ENTOMOLOGIST. 13 



observed does not warrant us in regarding the insect as beneficial, although 

 the predaceous habits and some correlated peculiarities of structure tend 

 to show that the imago may prove to be so. Upon what plant the larva 

 feeds is unknown. The mandibles of Allantus, as of many other saw- 

 flies, are asymmetrical, the teeth on the right mandible being more acute 

 than those on the left ; but the resemblance which they bear to the man- 

 dibles of Cicindela is very striking and would of itself suggest a similarity 

 of habits. 



Of the restricted genus Allantus two species occur in the eastern 

 United States, and, as they ha.ve not hitherto been clearly denned, I 

 append their distinguishing characters : 



i. Allantus basilaris. 



Tenthredo basilaris Say, Long's 2nd Ex., ii., 316 (1824). 

 A. basilaris Norton, Bost. Jour. N. H., vii., 240, 9 (i860). 

 " " Trans. Am. Ent. Soc. i., 361 (excl. var. 



a 2) (1867). ' 

 2 $ . Antennae short, black ; basal joint straw yellow. Markings 

 on legs and thorax clear yellow. 



°. . A large yellow spot on meso-pleura. 



$ . Abdomen yellow, posterior tarsi black ; pleura yellow, pectus 

 pale. 



2. Allantus dubius. 



A. dubius Nort., Bost. Jour. N. H., vii., 241, 10, °. (i860). 



" Tr. A. E. S., i.,362, $ (1867). 

 A. basilaris, var. a, £ Nort., Proc. Ent. Soc. Phila., iii., 10, 



18 (1864). 

 " Tr. A. E. S., i., 362 (1867). 



2 °. . Antennae longer ; ferruginous basal joints generally paler 

 Markings on legs and often those on thorax piceous yellow. 



°. . Meso-pleura black. 



2 • Abdomen black, the second, third and fourth segments yellow ; 

 posterior tarsi piceous yellow ; a small yellow spot on meso-pleura, pectus 

 black. 



2 var. (one specimen). Antennas black, a pale spot on pectus. 



In dubius the wings are darker and the size slightly larger ; the vertex 

 is more coarsely punctured, not so highly polished, and often it is orna- 



