1917] Pacific Coast Species of Xylococcus 159 



into the posterior end of the aHmentary canal. Two pairs of spiracles * 

 on thorax and eight pairs on abdomen; the former inconspicuous, the 

 latter with well developed stigmatal tubes (PI. XIV, fig. 3). Integument 

 smooth, after clearing in KOH seen to be covered with microscopic 

 pits increasing in size posteriorly; hairs sparsely scattered over cephalic 

 and thoracic areas, arranged in transverse rows segmentally on dorsal 

 and ventral surfaces of abdomen; a pair of backward directed lateral 

 spines increasing in size posteriorly on each abdominal segment; on 

 ventral surface of segment eight single lateral long bristles; pores of four 

 types — type I, a median ventral row of large pores anterior to anal tube 

 and varying in number from six to seven; type II, medium-sized lateral 

 pores on each abdominal segment dorsally and ventrally; type III, small 

 pores as follows, a pair on the mesothorax and a pair on the metathorax 

 ventrally, dorsally a pair on the metathorax, a pair on first abdohiinal 

 segment, and two pairs on the succeeding segments; type IV, very small 

 pores on dorsal surface of segments two to eight of abdomen (PI. XV, 

 figs. 13a and 13b). 



Female, second, third and fourth stages. — Color red, posterior end 

 of body brown, owing to chitinous nature of last abdominal segments. 

 Shape ovoid, broadest in thoracic region, bluntly rounded anteriorly; 

 abdominal segments well marked, posterior segments more compressed 

 than in stage one. Eyes represented by small black pigment spots 

 (disappearing on boiling in KOH), situated near, but not contiguous 

 to antennal discs. Antemice represented by microscopic chitinous 

 discs, bearing a few hairs varying in length and number. Legs wanting. 

 Rostrum large, situated about middle of body. Anal tube in second 

 stage with additional anterior spinnerets and a few median spinnerets, in 

 third stage with an increased number of spinnerets, in fourth stage 

 with two anterior circles of spinnerets and three median transverse 

 circles of spinnerets (PI. XV, fig. 14). Two pairs of thoracic and eight 

 pairs of abdominal spiracles, the former inconspicuous, the latter with 

 well developed stigmatal tubes, differing from those of first stage as 

 illustrated (PL XIV, figs. 3 and 6), and increasing in length in the suc- 

 cessive instars, one row of pores in constriction in second and third 

 stages and two irregular rows in fourth stage. Integument smooth, 

 after clearing in KOH seen to be covered with microscopic pits increasing 

 in size posteriorly; a few microscopic hairs on lateral areas; a few small 

 lateral spines posteriorly. Pores of two types (PI. XV, fig. 15); large 

 pores scattered sparsely on cephalic and thoracic areas; on abdomen 

 large and small pores arranged in transverse rows segmentally; small 

 lateral pores scattered on abdomen. In the successive stages hairs 

 and spines increase in size and pores in number. Pores much more 

 numerous in fourth than in preceding stages and arranged in bands 

 segmentally on abdomen. In all stages pores increase in number 

 posteriorly. 



Female, fifth stage, adult.- — Color dark red. Shape oblong-oval; 

 segments all well defined. Eyes small, black, laterad to antennae. 

 Antennae long and stout; nine-jointed; formula 1, 9, 2, (3, 7), 5, (4, 6, 8); 

 joints one to three stoutest; joints four to eight sub-equal; joint nine 



