324 FOREST ENTOMOLOGY. 



If a microscopical exanunation of the female Ije made in the winter 

 months, the well-developed rostrum will be observed, but a special ex- 

 amination of the anal segments forming the pygidium (fig. 303 (9)) 

 shows five groups of spinnerets and other important structures. 



It is well to bear in mind that the pygidium yields the main char- 

 acters wdiich form the principal basis for the discrimination of species. 

 The anal lobes, hairs, and other characters, requiring the highest 

 powers of the microscope, are all taken into account by the specialist. 

 Hence at this stage it may be as well to give detailed characters of 

 the female and pygidium of this species, as given by Newstead in 

 his Monograph : — 



" Adult female (fig. 303 (6)) elongate ovate ; cephalic, thoracic, and 

 abdominal segments strongly defined, the former being distinctly 

 triloliate. Colour dull crimson ; cephalic extremity dull orange, 

 mottled with crimson ; pygidium bright orange ; the dorsal spinnerets 

 indicated by a double semi -elliptic series of dull crimson marks. 

 Eyes black. Rudimentary antennae normal. Each of the three free 

 abdominal segments with about nine large tubular spinnerets at the 

 margin, of the same character as those of the pygidium ; and the last 

 segment presents a few^ stout, spiny plates. Pygidium (fig. 303 (9)) 

 has five large groups of circumgenital glands. 



" Dorsal tubular spinnerets, sliort and cylindrical, are in twelve 

 distinct series, forming three incomplete arches. Within the first 

 series, and immediately behind the lateral circumgenital glands, are 

 usually three other tubular spinnerets ; anus and vaginal opening 

 opposite. The median and second pair of lobes are well de- 

 veloped ; the former have the margins rounded, or faintly and 

 roundly serrate or dentate ; the second pair are bilobed, the anterior 

 lobule very small, and both have the margins rounded ; third pair 

 are also divided or bilobed, the posterior lobule usually dentate, the 

 anterior lobule very minute, and sometimes both are wanting. There 

 is a spine-like projecting pore between the median and second lobes ; 

 an angular one immediately posterior to the third lobe ; and there is a 

 third midway between the latter and the last group of plates. Two 

 long spines at the base of the anterior lobule of the second pair of 

 lobes. Of the plates, there is a short one between the median and 

 second lobes ; six others, long and spine-like, are arranged in three 

 pairs, and followed by a group of four or five others." 



It ought to be laid down as an axiom that only the full-grown 



