12 IVAR ARWIDSSON, SYSTEMATIC NOTES ON SOME MALDANIDS. 



Leiochone johnstoni Mc Intosh. 

 (Pl. 1, figs. 7—13.) 



1915. Leiochone johnstoni Mc Intosh (31, p. 319); ef., in addition, pp. 11 and 16. 



S p e c i f i c diagnosis. The cephalic plate very much reduced ; the lateral bord- 

 ers — on the whole rather wide — situated close to the keel and extending up to it 

 posteriorly. There are ocelli on the powerful cephalic lobe, even on the upper side; 

 specially prominent is a band on each side continuing posteriorly dorsally of the mouth. 

 The 7 th setigerous segment is rather long with the parapodia at its anterior part. The 8 th 

 setigerous segment is rather short, with the parapodia situated about half way nearer to 

 the posterior than to the anterior limit (measured along the ventral side); the anterior 

 limit of the segment is situated on the ventral side immediately in front of the lower 

 large glandular field, on the dorsal side somewhat farther posteriorly. Normally there 

 are 19 setigerous segments and 5 posterior achaetous segments. 1 middle ventral anal 



Text-tig. 1. Leiochone johnstoni. — Portion of the h*';i<l Text-fig. 2. Leiochone johnstoni. — Portion of the head 



seen from beneath. Ocelli. 23: 1. seen from the right side. Ocelli. 23: 1. 



cirrus, at most about twice as long as the anal cone; on each side of him 1 (in rege- 

 nerated individuals) — 2—3 anal cirri, more or less shorter than the preceding ones. 

 Setigerous segments 6—10 ha ve nephridia, whose orifices are situated somewhat behind 

 the lowest uncini. The 3 rd — 7 th setigerous segments ha ve a strong anterior band of 

 glands. The lower glandular field of the 8 th setigerous segment of larger specimens ex- 

 hibits the following collections of specially strongly stainable mucous glands: an angular 

 one near the anterior point and a small rounded collection on each side about half 

 way between the middle uncini and the anterior boundary of the field, straight in front 

 of the same setae; in small specimens one notices here, as in L. polaris, a patch free 

 from glands, which is gradually filled during growth with exceedingly strong glands. 

 A lower triangulär field between the lowest uncini of the two parapodia and with its 

 point directed forward, is rather sparsely glandular. The dorsal side of the 8 fch setig- 

 erous segment is furnished with 2 narrow bands of glands, which, issuing from the 

 posterior upper corner of the lower glandular field, converge anteriorly, extending herc 

 to the anterior limit of the segment; between the two parapodia there is here, in 

 addition, a narrow, not very well-defined, band of glands. The l sfc setigerous segment 



