THE OVIPOSITOR. 17 



Cladius viminalis, Hylotoma rosce, and Nematus luteus ; 

 while, contrariwise, wlien the eggs are laid in the 

 leaves they are slimly built, with the teeth and bars 

 not well developed, e.g. Nematus miliaris, or may be 

 scarcely represented, as with Nematus ribesii, which 

 simply glues the eggs to the leaf without making any 

 cutting. 



Outside the saw and its support, and serving as a 

 protecting case to them, is a two-jointed organ, which 

 projects to a certain extent out of the last abdominal 

 segment. The outer joint of this case is, as a rule, 

 differently coloured from the basal portion, is much 

 thinner than it, and hairy at the apex. At the base 

 the inner side is lengthened out, so as to follow the 

 curve of the basal joint, while at the apex it is rounded, 

 but not very sharply (PI. X, fig. 5). 



At first sight the basal joint looks as if it were 

 composed of one piece, but on dissection it is seen to 

 be composed of two. The main piece is longer than 

 broad, and curved to a point at each end, the lower 

 end being the sharpest. At the outer end of the 

 upper part is, firmly attached, a triangular plate, 

 which joins the whole to the base of the eighth abdo- 

 minal segment (PI. X, fig. 5, 1), the basal part being 

 thus composed of two pieces. 



The saw and the back piece are joined to the above- 

 described plates in the following way : The support 

 is attached, on the one hand, by its curved base to 

 the middle of the oblong plate on the inner side (fig. 

 4), while from its thickened rim there proceeds, not far 

 from the base, a thin wire-like structure, which goes 

 round the top of the " oblong " plate, to which it is 

 firmly attached close to the above-mentioned smaller 

 piece (fig. 5, 3). In a similar way a wire-like projection 

 proceeds from the base of the saw, above that of the 

 support, and fixes the saw to the triangular plate, but 

 it is not attached otherwise, save, of course, to the 

 support. 



The basal half of the sheath thus not only serves as 



VOL. i. 2 



