172 FOREST ENTOMOLOGY. 



believe, in conjunction with any of the phenomena described above 

 an 'oblique cross nervure' runs over (the apical portion of) the 

 humeral area, cutting it into two divisions, the apical one ' com- 

 pletely enclosed,' and very much smaller than the other." 



TENTHREDINID^E ( Leaf - wasps). 



This family is known in Germany by the name of " Blattwespen " 

 or Leaf- wasps, and the designation answers our purpose very well, 

 inasmuch as the larvae are always injurious (in very varying degrees) 

 to the foliage of many species of forest trees, but more especially to 

 Scots pine, larch, thorn, willow, and poplar. They are, however, only 

 injurious in the larval stage. 



The classification, for the purposes of the present work, of this 

 family is somewhat difficult, for two reasons (1) I need only to deal 

 with a few genera and species, taken as it were here and there from the 

 whole family ; and (2) the publication, now slowly proceeding, of a 

 very important German monograph of the saw-flies of the world has 

 already caused the abandonment in many cases of generic and specific 

 names hitherto employed in British works, and will doubtless yet 

 more disturb our present nomenclature within the next few years. 



I propose, therefore, to adopt the following merely provisional 

 division of the insects into three sub-families, according to Konow, 

 as follows Cimbicides, Lophyrides, and Nematides. 



CIMBICIDES. 



Genus Trichiosoma. 



The following are the generic characters according to Morice : 1 

 " Claws simple ; hind femora generally toothed conspicuously 

 beneath ; very pilose, brown-looking insects, with abdomen fuscous or 

 black above (but sometimes more or less rufescent at the apex and 

 beneath). 



" Synopsis op British Trichiosoma. 



1. Abdomen black, not bronzy; dull, closely and rather coarsely 

 punctured, and clothed right up to the apex with long, loose, 

 grey, sub-erect hairs. (Attached to the birch) T. lucorum, L. 



1 'Entomologist's Monthly Magazine' for Aug. 1903. 



