OK WASHINGTON. 44 I 



'/'he. spirt cs. 



These are long, stiff, black thorns, occurring on all the seg 

 ments, though but weakly developed on the prothorax and ctfh 

 abdominal, none on the loth abdominal segment. The subven- 

 tral ones are shorter than the subdorsal ones, and MM- upper spine 



on meso- ;inr] nict;tl!ior;ix ;is well ;is t.lie nnp;iired rnedi;ni spine on 

 the eighth ;iUlomin;il segment ;ne slightly longer th;in the otliei 



subdorsals and shortly forked at tip. The spines are smooth in 

 the case of the shorter ones ; the longer ones have from one to six 

 short side thorns or branches, 



The number of the spines. 



On the prothorax, one each side, above the base of the foot ; 

 on meso- and metathorax four on each side ; on the first to sixth 

 abdominal segments, rive ; on the seventh segment, four ; on the 

 eighth segment, one on the dorsal line and three on each side ; on 

 the ninth segment, two ; on the tenth segment (anal plates) no 

 true spines, but a lump on each side of the middle of suranal 

 plate. Two to three short spines on the leg-plates of the third to 

 sixth abdominal segments, 



The position of the spines. 



On the pedal abdominal segments the position is : First spine 

 subdorsally on third annulet ; second spine laterally on fourth an 

 nulet ; third spine substigmatally on second annulet ; fourth spine 

 upper-subventrally on fourth annulet ; fifth spine lower subven- 

 trally above base of foot (sixth annulet). On the first and second 

 abdominal segments the subventral spines are more remote and 

 more in line transversely, being both on the fifth annulet. On 

 the sixth and seventh segments the fifth spine is missing. On the 

 ninth segment the upper spine is lateral, the lower pedal, being 

 in front of the anal foot. On the thorax the first spine is subdorsaf, 

 the second lateral, the third substigmatal and a little anterior, the 

 fourth subventral. 



The homology of the spines. 



The position of these spinel leemi to indicate t.h;t. H,ey repre 

 sent the primary tubercles. Tubercle ii is not represented, and 

 there is an extra subventral spine on the third to sixth abdominal 

 nents; otherwise the position is exactly that of the seta? in 



st;i^r: I of ;my Spl.inx. '1 hetefoie. on t.ne pe<l;.l ;. f,domin;.l -.<'+- 



ments the first spine corresponds to tubercle i ; the second to 

 tubercle iii ; the third to tubercle v ; the fourth to tubercle iv ; the 

 fifth to tubercle vi (subprimary). On the thorax, the first spine 

 corresponds to tubercles ia + ib as proved by the cleft tip ; the 

 second to tubercle iia, lib being lost, or to iia -J- lib, the cleft tip 



