620 A. E. Verrill — Turbellaria, Nemertina, and 



is small, close to the margin. The stomach is large, in length about 

 equal to the oesophagus, long-elliptical, occupying 6 segments ; it is 

 covered with about 38 crowded rows of small, dark, round or ellipti- 

 cal glands. Color, yellowish white. Diameter of the type, .4™""; 

 the posterior half is lacking. Only one specimen was found. 



Opisthosyllis Langerhans, op. cit., p. 541, 1879. 



Palpi, body-segments, setre, and cirri as in Syllis {Typosyllis)^ 

 Oesophagus large and rather short, cylindrical, with the anterior 

 margin entire; median tooth near the posterior end. Stomach large, 

 its glands very distinct. Head pyriform, widest in front ; palpi 

 long and divergent. Buccal segment forms a collar. 



Opisthosyllis nuchalis, sp. nov. 



A large elongated species with numerous rather long, beaded cirri. 

 Oesophagus large, showing as a conspicuous, brown, oblong patch 

 on the back of the anterior segments. 



Head pyriform, widest close to the anterior margin, which is 

 truncate or slightly emarginate in the middle and on either side, so 

 that it is slightly four-lobed ; the sides are convex, narrowing back- 

 ward, the posterior end narrow with a small emargination between 

 two angular lobes. JEyes yellowish brown, small, nearly equal, 

 prominent, with a convex lens ; the anterior are wider apart, the 

 four forming a trapeze. Palpi large, divergent, longer than the 

 head, lanceolate, the distal half rapidly tapered, tips subacute, inner 

 margins excavated. 



The buccal segment is transversely narrow, and its anterior edge 

 is extended forward as a rather broad, thin collar, conspicuous on the 

 sides, where it extends as far forwai'd as the anterior eyes and almost 

 to the bases of the jjalpi, but receding dorsally, so as to expose the 

 posterior eyes. The first and second setigerous segments are a little 

 wider than the buccal and the breadth of the body suddenly 

 inci'eases at the third segment, where the end of the oesophagus is sit- 

 uated in the type specimen, but this is probably due, in part at least, 

 to the pressure used in mounting it. 



Tentacle and antennse are slender, tapered, strongly beaded with 

 small annuli, the distal ones are as long as broad, the proximal short 

 and indistinct ; the tentacle is considerably longer than the palpi, 

 and contains about 24 annuli ; the antennae are but little longer than 

 the palpi. Upper tentacular cirri are larger and about ^ longer than 



