MALDANIDAE 



167 



at the 8th as in the present species. O. dannevigi has 19 branchiate segments, and ac- 

 cording to Benham the ventral groove is continued as far forward as the head, though it 

 does not attain its full width till the loth chaetiger. This distinguishes it from the present 

 species in which the ventral groove begins suddenly at the 8th chaetiger. The Thora- 

 cophelia furcifera of Ehlers is a different species with bifid gills. 



Family MALDANIDAE 



1. Head without a cephalic border. . . 

 A cephalic border present 



2. Ventral acicular bristles in the first few chaetigers 

 No anterior ventral acicular bristles 



3. Ventral uncini present in ist chaetiger... 

 Uncini begin on the 2nd chaetiger 



4. Cephalic keel long, high and convex 

 Cephalic keel short and flat 



Genus Clymene, Savigny 



An oblique, bordered cephalic plate. Nuchal organs more or less parallel. Acicular 

 ventral bristles in the first three chaetigers. Dorsal bristles of two kinds. Pygidium 

 funnel-shaped and bordered with cirri. 



Anus sunk at the bottom of the pygidial funnel ; all anal cirri equal : subgenus Isoctrrus. 



Clymene (Isocirrus) yungi (Gravier). 



Isocirrus yungi, Gravier, 1911, p. 122, pi. ix, fig. 109; pi. x, figs. 115-120. 

 Benham, 1921, p. 106. 

 Monro, 1930, p. 171. 



Occurrence. St. 144 (i); 190 (i). 



Specific characters. There are 18 chaetigers and six achaetous ante-anal segments. 

 The cephalic plate is almost at right angles to the main axis of the body. There is no 

 cephalic keel. There is a pair of slightly divergent hook-shaped nuchal organs, in length 

 rather less than half that of the cephalic plate. Behind the nuchal organs the plate is 

 ridged transversely. The border is narrow and incised laterally. The part behind the 

 lateral incisions is crenate. 



For the first eight or nine chaetigers there are well-developed prechaetal glandular 

 bands, which in contracted specimens to some extent overlap the hinder borders of the 

 preceding segments. Farther back the prechaetal glandular bands diminish, but the 

 uncinigerous glandular pads increase in size and in the hinder region are very prominent. 



The first three chaetigers carry bundles of dorsal bristles and ventrally two or three 

 stout acicular bristles. The hooks begin at the 4th chaetiger. The dorsal bristles are of 

 two kinds: (i) narrowly bordered bristles with barbed tips, and (2) capillary barbed 

 bristles. The hooks have about four teeth above the main fang. 



The achaetous, ante-anal region is rather short, being equal in length to about the last 

 three chaetigers. The anus lies at the bottom of the anal funnel, which is surrounded by 

 a circlet of about 30 short, equal cirri. 



