190 SYLLIS ARMILLARIS. 



front, tapering to a lanceolate point posteriorly, and furnished with two cirri. It is 

 straw-yellow or slightly skin- coloured, streaked transversely by two lateral bars and a 

 central bar of greyish-brown in every segment, the effect being that anteriorly three 

 rows of dark touches are visible. 



The proboscis has a single conical tooth anteriorly, and about ten papillse on its 

 margin. 



The foot (Plate LXX, fig. 14) has dorsally a moniliform cirrus of ten to twelve 

 segments tapering towards the tip, barely equalling the diameter of the body, and 

 alternately carried horizontal and erect. Beneath is a short, bluntly-conical, setigerous 

 region bearing a series of stout spines, a point piercing the surface at the upper angle, 

 and a group of strong bristles (Plate LXXIX, figs. 8 and 8 a) with the shafts curved 

 towards the tip, which is bevelled, and bears a terminal piece of considerable length in the 

 anterior segments, a simple hook at the tip, and an edge covered with spikes (though 

 these are often worn). In the posterior segments the terminal piece is shorter; indeed, in 

 the anterior feet the upper bristles in each foot have longer terminal pieces than the 

 lower. The hooks of the bristles point upward. Ventrally is a lanceolate lamella (cirrus). 



In some a tuft of extremely fine, translucent bristles, above the jointed forms, 

 indicates the formation of the sexual stage. 



Habits. — It is a hard, stiff form, and comparatively sluggish, hiding under debris in 

 a vessel, or crawling slowly over the bottom. 



H. Rathke's Syllis tigrina 1 comes very near this form, and as subsequent authors have 

 not identified it, in all probability it refers to a variety of S. armillaris. 



The sexual form of this species is the Ioida macrojphtlialma of Dr. Johnston (1840) 

 and subsequent authors. The following example appears to pertain to the same form 

 as Dr. Johnston's, but there are certain discrepancies, so that further investigation is 

 necessary. 



Habitat. — On a laminarian blade covered with Obella from the West Sands, St. 

 Andrews, after a storm, October 25th, 1864. 



Head (Plate LX, fig. 2) small, with a slender median and two lateral tentacles, and 

 two large dark eyes. 



Body about three quarters of an inch long, with the segments and feet well marked. 



The foot in the first six segments presents no capillary bristles. Dorsally is the 

 moniliform cirrus of twelve or thirteen segments, tapering to the tip, then a considerable 

 interval, with the tip of a spine projecting from its surface. The conical setigerous region 

 has a group of jointed bristles, with simple hooked tips (hook directed upward) as in S. 

 armillaris, these tips being longer in the anterior bristles than in the median (Plate LXXIX, 

 fig. 9 a). A ventral lobe occurs beneath of an elongate conical form, thus differing from 

 the lobe in Syllis armillaris. 



This apparently is the form described by Dr. Johnston, but there is doubt, since the 

 long swimming-bristles are stated to be inferior and the jointed superior. This is 

 probably due to a misprint, 



1 < Beitr. Fauna Norweg./ p. 165, Taf. vii, f. 9—13 (1843). 



