156 



of course, state from which form of Ascidians these specimens were derived. 

 Thorell, who is the only author by whom this species has hitherto been ob- 

 served, obtained it from the branchial cavity of Ascidia venosa, and more 

 rarely from that of A. canina. 



Distribution. Bohuslan (Thorell). 



82. Lichomolgus furcillatus, Thorell. 



(PI. LXXXVI). 

 Lichomolgus furcillatus, Thorell, 1. c., p. 74, PI. XIII: 20. 



Specific Characters. Female. Body comparatively less slender than 

 in the 3 preceding species, with the anterior division sub-pyriform in outline. 

 Cephalic segment moderately expanded, and exhibiting behind a well-marked 

 transverse suture. Tail scarcely exceeding half the length of the anterior 

 division; genital segment comparatively large and somewhat dilated in the 

 middle, with the anterior and posterior parts well marked off from each other 

 laterally; anal segment rather small, broader than it is long. Caudal rami not 

 much produced, scarcely exceeding in length the last 2 segments combined, 

 and of nearly equal width throughout; seta of outer edge well marked and 

 attached at about the middle; apical setae less rudimentary than in the pre- 

 ceding species, though scarcely ciliated, the inner mediate one almost as long 

 as the corresponding ramus; dorsal bristle well marked and attached near the 

 end. Anterior antennae about the length of the cephalon, and of the usual 

 appearance. Posterior antennae resembling in structure those in L. albens, 

 except that the proximal bristle of the penultimate joint is replaced by a strong 

 spine. Oral parts on the whole normal. Natatory legs likewise built on the 

 very same type as in the preceding species. Inner ramus of 4th pair of legs 

 somewhat longer than the first 2 joints of the outer combined; distal joint, as 

 in L. albens, attenuated in its outer part, and having the inner apical spine 

 rather long. Last pair of legs with the free joint comparatively larger than 

 in the preceding species, and exhibiting a well-marked notch in the middle 

 of the outer edge; both apical setae spiniform, the posterior one the longer. 

 Ovisacs rather large, extending far beyond the end of the tail. 



Male with the posterior maxillipeds very powerfully developed, inner 

 edge of the propodos produced in the middle to a small papilliform promi- 

 nence; dactylus long and slender, being abruptly curved at some distance 

 from the base. 



Colour whitish. 



