Ophkni] BRITISH ICHNEUMONS. 265 



It is entirely open to question how far the description of various forms 

 of Ophion luteiis serves any good purpose. Their stability can only be 

 ascertained in a positive degree by breeding, and even therein the resultant 

 parasites are doubtless influenced to an unknown degree by the vicissi- 

 tudes through which their hosts of varying size may happen to pass. 

 However, Thomson, Kriechbaumer and Brauns have split off certain 

 forms under specific names and all of them are comparatively recognisa- 

 ble, for nothing but distinction is necessary in description of so closely 

 allied species or forms of a species as those of this restricted genus as 

 now understood. In the examination of mv two hundred and fifty exam- 

 ples of this small group I obtained sufficient experience to convince me 

 that the minor distinctions of relation between upper and lower basal 

 nervure, angulation between basal and apical abscissae of radius, etc., 

 were of little stabilitv and that neither the exact development of meta- 

 notal carinae nor approximation inter se oi\k\^ ocelli could be relied upon. 

 I have retained U. obsciinis as a single species, though the mandibles are 

 occasionally acute or obtuse, pointing to either the existence of two 

 species under this name, or instability of mandibular structure to which 

 I am not inclined to give credence. Thomson's species are perfectly 

 good, though the mandibles will more satisfactorily distinguish one from 

 O. luleus than the scutellar carinae, which seem to me of variable develop- 

 ment and not always present. 



Tabic of Species. 



[2%'). I Radius basally straight and not at 

 all incrassate [ Ophion, sciisii 

 sfricfo\. 



Wings subhyaline ; petiolar mem- 

 brane nearly reaching spiracles. 



Mesonotum unicolorous or with no 

 bright fiavous lines. 



Mandibular teeth subacute and not 

 short ; scutellum laterally immar- 

 ginate. 



Metanotal areola complete ; stigma 



centrally stramineous .. i. M(K■s,\K^!, B)-aii>is. 



Metanotal areola not indicated; stig- 

 ma always darker. 



Stigma clear testaceous throughout ; 

 third segment not strongly con- 

 stricted. 



Basal metanotal transcarin.a distinct ; 

 species large. 

 9. Ocelli touching eyes ; cheeks obso- 

 lete ; vertex distincti)' narrow. 



Hmd calcaria linear throughout ; 



ocelli collectively subpyramidal 2. i.r iKls, Linn. 



Hind calcaria basally incrassate; 



ocelli distinct />//<'r .rt" .. }>• CALCAR.ATUS, il/c;r/. 



Ocelli remote from eyes ; cheeks long; 



vertex broader 4- I>1ST.\NS, 'J'/iotns. 



Basal metanotal transcarina wanting ; 



species small .. • .'>• I'AK\'ri.rs, /wvir//. 



Stigma ferrugineous, always basally 

 white ; third segment constricted. 



Antennae filiform, not longer than 



half body; temples broad 6. I'orticorni.s, J/i^vr/. 



S2 



