87 



powerful development of the maxillipeds. According to Giesbrecht, the Ascomyzon 

 Lilljeborgi of Canu is not this species. 



Occurrence. Boeck found this form on a specimen of Echinaster sang- 

 vinolentus taken at Farsund, south coast of Norway. I myself, many years ago, 

 collected some specimens off the west coast, and, as far as I remember, from 

 our common Asterias ntbens. 



Distribution. British Isles (Brady, Scott). 



50. Aseomyzon Lilljeborgi, Thorell. 



(PI. LIII). 

 Ascomyzon Lilljeborgi, Thorell, Bidrag til kanneclomen om Krustaceer, som levfa i arter af slagtet 



Ascidia, p. 78, PI. XIV, fig. 21. 

 Syn: Asterocheres siphonatus, Giesbr. 



Specific Characters. Female. Anterior division of body moderately ex- 

 panded and rounded oval in outline, the greatest width not nearly attaining the 

 length; epimeral parts of the segments less prominent than in the preceding 

 species, and rounded at the end. Cephalic segment only slightly longer than the 

 4 succeeding segments combined, and narrowly rounded in front; rostrum distinctly 

 defined, though not prominent, and blunt at the tip; lateral edges of the segment 

 infiexed. Tail scarcely exceeding in length 1 / 3 of the anterior division; genital 

 segment less broad than in A. asterocheres, and exhibiting on each side, immediately 

 behind the genital orifice dorsally, a knoblike projection; anal segment only slightly 

 longer than the preceding one. Caudal rami very short, being scarcely longer than 

 they are broad; apical setae of moderate length. Anterior antennae long pnd slender, 

 even somewhat exceeding in length the cephalic segment, and composed of 19 

 joints, the outer 2 joints only of the terminal part being coalesced. Posterior 

 antennae less strongly built than in A. asterocheres, with the penultimate joint 

 rather narrow. Oral cone produced to a long and narrow siphonal tube extending 

 almost to the middle of the genital segment, the tube, for the greater part of 

 its length, being finely striated transversally; tip slightly dilated, spoon-shaped. 

 Mandibles with the masticatory part greatly prolonged in accordance with the 

 great length of the siphon; palp comparatively smaller than in A. asterocheres. 

 Maxillae with the inner lobe moderately produced and rounded at the end, outer 

 lobe scarcely more than half as long and much narrower; setse of the lobes not 

 particularly strong and rather unequal in length. Maxillipeds less powerfully 

 developed than in the preceding species, the claw of the anterior ones com- 

 paratively short and only slightly curved at the end. Natatory legs resembling 

 in structure those in the said species, but of somewhat larger size. Last pair 



