248 ZOOLOGISCHE MED EDEELINGEN — DEEL IV. 



ones the dorsal ligule is enlarged to a conical lobe, with a transversely- 

 folded epidermis, bearing the dorsal cirrus upon its tip; the setae have 

 acquired the character of vitreous swimming bristles, the terminal piece 

 of which however is narrower and more acute than that of the ordinary 

 cultrate setae. The ventral lobe is provided with a conical anterior lip, 

 that is somewhat longer than the ventral ligule, whereas its posterior lip 

 is rounded triangular. In the posterior body-region the dorsal cirrus is 

 long and slender, born upon the tip of a conical ligule; the ventral cirrus 

 extends only to half the length of the neuropodium. Both foot-lobes are 

 conical, the dorsal one somewhat more slender and longer than the ventral 

 one; the ventral ligule has nearly totally disappeared and is represented 

 by a conical tubercle. 



The head is almost twice as broad as long, with two pairs of coales- 

 cent eyes, which are of unequal size, the anterior of them being smaller 

 than the posterior ones. The palps, that are provided with a slender, 

 cirrus-like distal joint, are about as long as the antennae. The tentacular 

 cirri are short, the longest of them reaching only to the 4th segment. 

 In none of both specimens the proboscis being protruded, this organ had 

 to be dissected out; no horny paragnaths were visible, only two soft 

 papillae could be recognized on the oral region and two maxillae of the 

 ordinary type. The maxillae are without denticulations, only its internal 

 edge is indistinctly crenulated. 



One specimen, with an incomplete anal end, measured about 16 mm. 

 in length; the other one was broken in two pieces. 



Nereis onychophora n. sp. 



Siboga-expedition, Stat. 172, off Gisser, Ceram Laut isles. 



Among the plankton-worms, collected at the above-named station, I 

 met with a male Heter oner eis, that is characterized by having in the 

 anterior (agamous) body-region, the notopodial fascicle repre- 

 sented by a single, stout, yellow bristle, with a dark 

 brown, hook-shaped apex; the neuropodial fascicle has its usual 

 appearance and contains in its dorsal part some homogomph setigerous 

 bristles and some heterogomph falcigerous ones, whereas ventrally there 

 occur only falcigerous setae, with a terminal piece, that is ciliated along 

 its whole border. The aciculae are blackish. The dorsal ligule is very 

 small, papilliform and bears a cirrus, which is much longer, extending 

 somewhat beyond the extremity of the notopodial lobe, that is large, 

 obtusely conical. The neuropodial lobe has a conical anterior lip and 

 reaches beyond the extremity of the ventral ligule, that is club-shaped. 

 The ventral cirrus is as long as the inferior ligule. In the anterior 5 



