EREANTIATE POLYCHAETA OF JAPAN. 135 



on tlio loffc great dental plate varies from 3 to 5, thongli usually 

 it bears, as does always the riglit, 4 teeth. 



Habitat : — Misaki (!) ; Tatoku-jima in Prov. Sliima (!) ; 

 Yenoshima in Prov. Sagami (Marenzeller). 



Genus Coelohranclius n. g. 



Prostomium witli 2 tentacles. Eyes invisible. Two anterior- 

 most segments lack parapodia. Tentacular cirri absent. Para- 

 podium uniramous, witli simple and compound bristles. Branchiae 

 branched. Extensions of the alimentary canal enter into the 

 cavities of branchial filaments. Anal cirri 2. Both halves of 

 maxillary apparatus with an unequal number of jaw-plates. 



Coplohranchus lyapillosus n. sp. 



PI. XV, figs. 1—7. 



Body slender, tapering to both anterior and posterior ends ; 

 the branclied gills, wliicli cover almost entirely the dorsal 

 surface of body, appear just like the dorsal cerata of an eolid 

 mollusca. 



Tlie coloiii' is almost wliite, except tlie gill filaments and the 

 dorsal median line, bntli wliicli arc tinted with luMnvn. 



One of llie largest female specimens is represented in fig. 

 1, Plate X\\ it measures 120 mm. in length and ■"> mm. in 

 Tiiaxiiiiuni lircadlli: the segments number 20S. The male is 

 irenerallv smaller than the female, the l'eianer Ç(^nsistinL: of 150- 

 180 and the laKcr of li').") -JIO segments. 



i'rostominm nearly :> times as bnnid as long, with convex 

 and smeoih anjcriei' mai'gin : ])r(ivide(l with 2 small tentacles. 



Peristnminm, consistinu" el" 2 similar segments, each of these 



