1M PIONOSYLLIS (SYLLIS) HYALIXA. 



to about the thirty- sixth segment show marked ciliation internally, with a violet colour in 

 the wall of the internal trumpet (pavilion), and orange at the external aperture at the 

 base of the feet. At the same time a clear spine and a group of swimming-bristles 

 develop beneath the dorsal cirrus. 



Advanced ova occurred in a female from Herm in July, and indeed, the example 

 appeared to be almost ripe. 



Habits. — The species is somewhat smaller than Gastalia fusca and is at once 

 distinguished by its brown colour. It is active and lively, wriggles through the water 

 with the usual vigour of a Hesione, and is irritable and fragile. Those obtained broke 

 into fragments. 



So far as can be determined this species is that originally described by Keferstein 

 from St. Vaast-la-Hougue, and subsequently by Claparede as Syllis normannica, and 

 though it is true Langerhans states that it has a simple tip to the terminal piece of its 

 bristles, it is more likely that this feature — often so indistinct— was misinterpreted than 

 that two forms so nearly identical exist on the shores of the Channel. The additional 

 distinction given by De St. Joseph, viz. the structure of the first segments, would not 

 seem to invalidate the foregoing conclusion. 



The occurrence of a spine for the support of the swimming-bristles, and the structure 

 of the distal piece of the compound bristles, give the form an intermediate character — 

 approaching the Syliids most closely, but also leaning to the Hesionidse. It may be 

 placed provisionally in this group. 



De St. Joseph (1886) found Trichodina Auerbachii attached to the tentacles and feet. 



j 



3. Pionosyllis (Syllis) htalina, Ghrube, 1863. Plate LI, fig. 2; Plate LXX, fig. 24- 

 foot; Plate LXXVIII, figs. 9 and 9 a— bristles. 



Specific Characters. — Head subpentagonal ; eyes four, dark-reddish, arranged in a 

 trapezoid, anterior pair larger and wider apart and in some with lenses, posterior close 

 together, occasionally with a small additional pigment-speck in front on each side. Palpi 

 large, somewhat triangular. Median tentacle rather longer than the lateral, and all 

 distinctly articulated (about twenty segments). Buccal segment slightly narrower than 

 the succeeding. Tentacular cirri about the length of the dorsal cirri, a little longer than 

 the breadth of the segment. Body about 18 mm. long (Grube), 90—127 segments, 

 hyaline, showing the gut. Cutis dense and iridescent, occasionally with a pinkish-yellow 

 colour. Two long anal cirri, thicker than the dorsal cirri, and much longer, with a 

 median papilla. Feet with moniliform dorsal cirri, the articulations ranging from twelve 

 to sixteen, but some are alternately shorter ; about half the breadth of the body-segment. 

 Setigerous lobe forming a short bilobed cone — the spines piercing its apex, which is 

 superior— leaving the longer curve inferiorly. About ten falcigerous bristles in the 

 setigerous region, the terminal piece elongate and slightly curved. The jointed bristles 

 occur beneath the spines, and have shafts with a marked distal curve and a bevelled dilata- 

 tion, the convex edge of which has traces of serrations. The terminal piece is somewhat 



