FAMILY SIRICIDJ). 125 



the middle lobe of niesonotum being continuous with 

 the scutellum. 



(3) In the two supports of the ovipositor being firmly 

 soldered together, forming an almost closed tube. 



The differences between the ovipositors of Tenthredo 

 and Sir ex are two ; they are not broad and toothed ; the 

 two pieces I have called in the Tenthredinidw the 

 supports, and which with these are separate, have here 

 become soldered together forming a hollow channel (but 

 not a complete tube), inside of which the stilets (=the 

 cutting saw of Tenthredo) lie, almost completely filling 

 the cavity of the " borer/' A reference to the figure on 

 PI. VII, fig. 6, Vol. II, and a comparance of it with the 

 ovipositor of Cephus or with Trichiosoma on PI. X, fig. 5, 

 Vol. I, will show that in general structure these are 

 quite identical. The " triangular plate," by means of 

 which the instrument is attached to the last abdominal 

 segment, is small, hollow on the inner side, and has a 

 stout outer border for the attachment of the muscles. 

 The sheath is long and narrow, and becomes still 

 narrower as the apex is reached. Like the triangular 

 plate it is hollow internally, so that when the two pieces 

 are brought together they form a tube, completely 

 enclosing the borer and the spicules. At its junction 

 with the triangular plate it has on the inner side a 

 strong wire-like process, and a similar one runs at 

 right angles from it to the opposite side, where the 

 borer is attached to it. The lateral plate (= oblong 

 plate of Tenthredo) ends where the ovipositor leaves 

 the abdomen, and here there is a strong ligature binding 

 the whole. As stated above the two separate supports 

 of the ovipositor have amalgamated, and form a long, 

 narrow, thin tube, marked with oblique bars at the 

 apex. The spicules have the same form and have like- 

 wise projecting points at the apex. They fill the borer 

 completely, and as the latter is quite rigid and has no 

 flexibility except from the abdomen, it is obvious that 

 the spicules can only have an up-and-down movement. 

 The attachment of these pieces to the sheath is as in 



