BRITISH ICHNEUMONS. 



Plec/isciis was placed next before Porizon by Marsliall in his 1872 Catalogue 

 and, with Helictes, next aftcT IMcsochorus b}- Desvii^nes in 1856. Helic/cs, 

 however, is synonymiscd in the former catalogue with i\Iegastv/iis and 

 Holmgren is there followed in its certainly erroneous transference to the 

 Trvphoninae. In fact the present group, in reality by no means 

 homogeneous, consists largely of three genera widely separated in the 

 Catalogue : Plectiscus among the Ophioninae, i\lcgastv/ns among the 

 Tryphoninae, and Clcpikus, with which I have succeeded in satisfactorily 

 svnonymising Prodi/us, among the Xoridides, with which it has no 

 relation. In the last European work upon this Tribe we find here 

 included Adelognn/hus, Phidias and AcrodactyJa, which I have already 

 treated of in former volumes. 



Some of the older descriptions are too vague to place in the highly 

 specialised genera now adopted, and I have had to entirely omit both the 

 central European Pkciiscus flavopicins, Grav. (I.E. ii. 983), which was 

 thought by Forster (in his " Uebersicht der Gattungen und Arten der 

 Familie der Plectiscoiden," 1871, p. 103) to belong to his genus Myriar- 

 thrus, both for lack of its true position and evidence of indigenous 

 occurrence; and the German Plectiscus impurator, Grav. (I.E. ii. 982), 

 thought to be an Hclictes by Haliday (in his paper on " New British 

 Insects indicated in Mr. Curtis's Guide," p. 115) in 1839, to be the type 

 of his Orthocentrid genus BlepJioctonus by Forster in 1871 and to probably 

 be iMegasfylus pumilio by Thomson (in his admirable " Forsok till grup- 

 pering af slagtet Plectiscus, Grav.") in 1888. I have tentatively synon- 

 ymised P. zonatiis with P. caiialicjilaius, Forst., though the compound 

 description doubtless in part belongs to the genus Prolictus ; the 

 S3-nonymy of Helictes variiis, apparently allied to Idioxcjuis coxalis, has yet 

 to be worked out; of P.pallidipcs, Grav., said by Schmiedeknecht (Opusc. 

 Ichn. 2202) to probably be an Hemiteles, I have already treated (Ichn. 

 Brit. iv. 316). 



I have adopted all the available genera of this Tribe, both on account 

 of the unusually lucid method in which Forster elaborated them and 

 because so few of our species have yet been recognised that they will 

 eventually become necessary for the convenient grouping of the remaining 

 mass. 



Hardly anything is yet ascertained of the economy of this Tribe ; its 

 members are said to exclusively prey upon Diptcra, mainly of the Nema- 

 tocerous families jMycetophilidae and Tipulidac ; I have been enabled to 

 confirm the former association; but it is appalling how little wc yet know 

 concerning Ichneumonidous economy. 



7 able of Gencr'a. 



(6). I. Front wings with areolet more or less 



distinct and entire. 

 (5). 2. Metathorax with verj^ distinct discal 



areae. 

 [.\^u 3. Clypeus entirely deplanatethrou.ghout HoLOMRRlSTrs, i^Jr^-/'. 

 (3). 4. Clypeus convex and laterally subcom- 



pressed . . Plfxtiscus, Grav. 



(2). 5. Metathorax glabrous with no trace of 



areae . . . . . . . . Aperileptus, Forst, 



(i). 6. Wings with no trace of areolet, its 



inner nervuro sornetimes wanting. 



