618 A. E. Ven-ill — Turhellaria, Nemertina, and 



Head small, the anterior portion nearly semicircular, deeply emar- 

 ginate or cordate behind, well rounded in front, but with a slight 

 median lobe, sides evenly rounded, most convex opposite the eyes, 

 which are about equal, rather small, black, airanged in a short 

 trapeze, the distance between the anterior and posterior about equal 

 to two diameters ; a pair of minute black ocelli at the anterior mar- 

 gin in front of the antennae. 



Palpi large and long, lanceolate, regularly tapered, longer than the 

 head, obtuse. Tentacle shorter than the antennae, of 8 annuli, 

 equal to the palpi, tapered, its distal annuli longer than broad. 

 Antennae similar, but about ^ longer, of 13 annuli, about 3 or 4 

 distal annuli projecting beyond the palpi. Tentacular cirri long and 

 slender with rounded annuli, about as long as broad ; upper ones, 

 with 18 annuli, are longer than the antennae, lower ones about f as 

 long. Dorsal cirri of segments 1, 3, 4, 6, and many others are longer 

 than the tentacular cirri, composed of 22-28 annuli, and about twice 

 as long as the diameter of the body ; shorter ones irregularly alter- 

 nating are 1^ to f as long. Caudal cirri long and slender, tapered, 

 similar to the longer dorsal cirri. 



Setae rather numerous, long and slender, all compound and sim- 

 ilar ; the upper anterior ones have slender lanceolate blades with 

 bidentate tips, ratio about as 1 : 4 or 5 ; of the lower ones about 

 1 : 3 or 4. Posteriorly the blades are shorter and the tips are more 

 incurved and more strongly bidentate, with the denticles divergent, 

 ratio about 1 : 2-2^ ; these are usually accompanied by 1 or 2 rather 

 stouter spiniform acicula, with the tips slightly projecting, that of 

 one usually somewhat hooked, the other only a little bent. 



The oesophagus is rather long, occupying 8 segments, but not 

 slender, wrinkled transversely in the type and somewhat contracted 

 at each end ; its margin is emarginate on each side and is divided 

 into a number of rather small, not very regular, obtuse denticles or 

 scallops ; the tooth is close to the edge and rather small ; the soft 

 pharynx is divided into a circle of rounded lobes. The stomach is 

 elongated, narrow, cylindric, occupying 8 segments, about equal in 

 length to the cesophagus, and not much larger ; its surface is covered 

 with 50 to 55 close rows of opaque cell-groups ?. Color, in formalin, 

 plain yellowish white. Length, about W^"^ ; diameter, .6°^™. 



This species is very distinct from T. vittigera Ehlers, which is 

 a large brownish species conspicuously marked by two transverse, 

 narrow, white bands on each segment, and with the denticles of the 

 oesophagus large and subtruncate. The setae have short, bidentate 

 blades. The latter was taken by us in considerable numbers. 



T. gigantea Mclnt. (Chall. Voy.) as Syllis, appears to be closely 

 allied to this last species. 



