BY W. A. HASWELL. 93 



Syllis (TyposYLLis) PECTiNAN'.s, 11 . sp . (Plate X., tig. 3-6). 



AVIic'u alive and fully extended this is a slender, almost thread-like worm, 

 measuring, in the case of the larger specimens, about 1.5 to 2 cm. in length. The 

 colour varies considerably, the differences being due mainly to differences in the 

 colour of the intestine as described below. The body-wall may be transparent and 

 colourless, but usually there are widely-diffused minute particles of reddish-brown 

 pigment, most abundant in the dorsal integument in the anterior region, where, 

 in some cases, they tend here and there to become arranged m very irregular 

 transverse lines stronger towards the anterior and posterior limits of the segment. 

 The pigment may be scattered also through the tentacles, palpi and cirri, but 

 sometimes these appendages are completely colourless. 



The tentacles and cirri contain numerous sausage-shaped glands which are 

 usually extremely bright and conspicuous in the living animal. Sensory cilia are 

 abundant on the tentacles, palpi and dorsal cirri, less abundant on the ventral 

 cirri. Vibratile cilia run along the sides of the segments between the parapodia. 



The prostomium is broader than long, elliptical in general outline. The pig- 

 ment which it usually bears dorsally, is irregularly distributed. The eyes are 

 always comparatively small, and a frontal pair is rarely present. The palpi are 

 entirely separate, though in close contact in their basal portions. The median 

 tentacle is the longest — about five times the length of the prostomium, with about 

 35 well-defined joints; the lateral about thrice the lengfh of the prostomium, with 

 about 25 joints. 



The peristomium appears on the dorsal surface for a narrow space only. 

 The dorsal peristomial tentacles are about equal in length to the median, and have 

 about the same number of joints; the ventral are a little shorter. 



There are about 60-70 segments in the body before stolonisation begins. 



The parapodia (Plate x., fig. 4) are not very prominent, less than half the 

 breadth of the body, slightly bilobed, the anterior lobe much the more prominent. 

 Each contains about 10 or 12 compound setae (Plate x., fig. 5) which vary little 

 in character throughout. Their falces are all relatively short, unidentate, with a 

 fringe of unusually strong, pointed processes along the cutting edge, those to- 

 wards the apex becoming very rudimentary. There is a simple seta (Plate x., 

 fig. 6) on the dorsal side of the compound in all the posterior parapodia: in a 

 specimen of 67 segments without definite stolonisation these begin on the 26th 

 segment, and are continued to the posterior end ; in a female specimen of about 

 60 segments with a stolon, they begin four segments in front of the stolon (on 

 the 40th segment) ; in another similar specimen they begin nine segments in front 

 of the stolon. They are similar to the simple setae of ,9. variegata — gently curved 

 towards the free end, pointed, obscurely bidentate, and with four or five cilia on 

 the concave edge of the terminal curved region. In three or four of the last 

 segments a simple bidentate seta occurs on the ventral side of the bundle of com- 

 pound setae : this is finer and shorter than the dorsal simple seta, and does not 

 seem to be always present. 



In specimens with mature stolons, bundles of capillary setae occur on all 

 the segments of the stolon; when fully developed these are twice or thrice the 

 length of the compound setae. 



There are four acicula (Plate x., fig. 4) in each of the most anterior para- 

 podia, three or two in the rest; all are knobbed at the ends with the knob usually 

 sharply bent, but towards the dorsal side, so that the bend is not readily per- 

 ceptible. 



