THE AXAL APPENDAGES. SPIRACLES. 19 



The male anal appendages undoubtedly might be 

 made to furnish specific characters, but they are very 

 minute, and difficult either to describe or figure, so I 

 have not mentioned them in the descriptions of the 

 species. 



The spiracles are nine in number. The first is 

 placed on the prothorax, close to its union with the 

 mesothorax, and a little way down from the tegulas. 

 The second is on the metathorax, close to the meso- 

 thorax ; the rest are on the first to seventh abdominal 

 segments. They are always placed on the front of 

 the segment, and on the abdomen are situated on the 

 upper edge immediately below the back. 



With the larvae the first segment bears a spiracle ; 

 the next is on the footless fourth segment, the rest on 

 segments five to eleven. 



The outer covering of the imago is generally smooth 

 and somewhat shining, rarely is it punctured to 

 any extent. A few forms have hairy bodies, e.g. 

 Trichiosoma. Many (especially exotic species of the 

 Hylotomina) have their bodies of a decided metallic 

 lustre. 



As for colour, it is generally black or some shade of 

 it. Some are coppery-green or blue ; a few green 

 without any metallic reflection, e.g. Tenthredo punc- 

 tulata ; yellow or some shade of it is not uncommon 

 with Nematina and Hylotomina. The legs are often 

 differently coloured from the rest of the body ; red is 

 a not uncommon colour for them, and, as a rule, the 

 tarsi are black, or darker coloured than the other 

 parts. The antennse may be either uniformly coloured 

 or paler on the under side, more rarely they are orna- 

 mented with white rings. 



There is one curious point about the coloration 

 pattern in these insects which deserves notice, namely, 

 that many species belonging to widely separated 

 genera are coloured alike. Especially is this the case in 



