NO. 1206. ICHNEUMON FLIES— ASHMEAD. 77 



Mesonotum, scntellum, and first three alKlominal segments not coriaceous. 



(588) Sdvajryrlma Fikster. 



77. ( )ccipital margin interrupted medially (589) Apystus Forster. 



Occipital margin not interrupted medially. 



First abdominal segment with carinse extending froni the spiracles to the 

 apex . 78 



First abdominal segment tinthout caringe extending from the spiracles to the 

 apex (590) Doliocionus Forster. 



78. Metanotum with more or less distinct' carina? 79 



Metanotum uithout trace of carinas antennre ringed with white. 



(591) Bari/larhcs Forster. 



79. Basal joint of hind tarsi not thickened; longer spur of hind tiV)ia> fully half as 



long as the basal tarsal joint 80 



Basal joint of hind tarsi somewhat thickened; longer spur of hind tibise not 

 half as long as the basal tarsal joint (592) Holmgrenia Forster. 



80. Mesonotum dull, finely shagreened 81 



Mesonotum not shagreened (593) Lathrophagus Forster. 



81. Clypeus with the anterior margin laterally more or less impressed, and more or 



less distinctly interrupted (594) Campodorus Forster. 



Clypeus with the anterior margin laterally more or less distinctly transversely 

 impressed, the front margin distinctly separated and more or less 

 deeply emarginated (595) Mesoleius Holmgren. 



Tribe V. BASSINI. 



1855. Tryphonides schizodonit Holmgren, Svensk. Vet.-Akad. Handl., I, \k 98; 



II, 1856, p. 353. 

 1868. Bassoid?e, Family 14, Forster, Verb. <1. naturh. Ver. pr. Kheinl., XXV, 



I)p. 142 and 162. 

 1890. Bassina, Tribus, Thomson, Opus. Ent., XIV, p. 1463. 



1894. Bassini, Tribe V, Ashmead, Proc. Ent. Soc. Wash., Ill, p. 277. 



1895. Basdni, Tribe, Davis, Trans. Am. Ent. Soc, XXII, p. 17. 



1900. Bassini, Tribe V, Ashmead, Smith's Insects of New Jersey, p. 579. 



This group, with its sessile abdomen and in having two distinct 

 apical spurs on the middle and hind til)ia?, as well as in venational 

 characters, agrees with the (Jtejwpelmini and the Tryjyhonini, but 

 from these tribes, as well as all the other tribes, it is at once distin- 

 guished by the mandibles, which are always tridentate at apex, never 

 bidentate. 



The species belonging to the group, whose parasitism is known, so 

 far as authentic records go, seem to confine their attacks to the larva? 

 and puparia of Dipterous insects, and almost without exception to 

 those in the family Syrphidce. 



The tribe is of small extent, only ten genera being known, but some 

 of the species, and especially those in the typical genus Bassus, have 

 a world-wide distribution. JBassus ketaforius Fabricius has been taken 

 in Pvurope, Africa, Asia, Australia, New Zealand, Chatham Islands, 

 Hawaii, Japan, the West Indies, and in North and South America. 



All that is essential for distinguishing the genera may be foimd in 

 the following table: 



