57. Rhynehomyzon purpurocinetum, (Scott). 



(PI. LXI). 



Ciiplopicera purpurocincta, Scott. Eleventh Ann. Eep. of the Fishery Board for Scotland. Part III 



p. 209, PL III, figs. 29-40 



Specific Characters. Female. Anterior division of body rather strongly 

 vaulted above, and oblong oval in outline, greatest width scarcely exceeding half 

 the length. Cephalic segment large, being fully twice as long as the 4 succeeding 

 segments combined, aud having the frontal edge narrowly arched, epimeral edges 

 of the segment evenly curved in front and strengthened behind by a number 

 of transverse chitinous stripes. Rostrum very conspicuous in the lateral aspect 

 of the animal, and produced to a sharp point. Epimeral parts of the 2 succeeding 

 segments terminating behind in acute corners. Tail about equalling in length 

 2 /s of the anterior division: genital segment almost cylindric in form, with a very 

 slight angular prominence on each side of the anterior part; 2nd segment almost 

 as long as the 2 succeeding segments combined; anal segment the smallest. Caudal 

 rami rather produced, somewhat exceeding in length the last 2 segments com- 

 bined, and slightly divergent, outer edge smooth, inner finely ciliated; apical setse 

 comparatively short, the innermost but one scarcely exceeding twice the length 

 of the corresponding ramus. Anterior antennae rather narrow, but much shorter 

 than the cephalic segment, and composed of 16 joints only, 2nd joint the largest 

 and apparently formed by the fusion of 4 short joints: terminal part biarticulate. 

 Posterior antenna with the penultimate joint scarcely half as long as the pre- 

 ceding one; apical spine rather slender. Oral cone very massive and rather 

 prominent below; anterior lip terminating in a somewhat curved point. Mandibles 

 with the masticatory part pronouncedly knife-shaped and minutely denticulate 

 inside the tip. Maxillse with the outer lobe nearly as long as the inner, but 

 much narrower, linear in form; setse on both lobes comparatively short. Max- 

 illipeds moderately strong. Natatory legs exhibiting a similar armature to that 

 in Dermatomyzon nigripes. Last pair of legs with the distal joint oval in form 

 and subtruncate at the extremity, which carries 2 thin bristles between which 

 a somewhat larger lanceolate spine is attached; posterior edge of the joint finely 

 ciliated and having on each side of the innermost bristle a slight dentiform 

 projection. 



Male much smaller than female, but not very different in the general 

 form of the body. Tail, however, somewhat more slender and composed of 5 

 well-defined segments, the foremost of which (the genital segment) is compara- 

 tively smaller than in most other forms of the present section. Anterior 



