POLYCIRRUS AUPANTIACITS. J 95 



yellow hue. Their extensibility and elasticity are remarkable, and the thinnest strand 

 presents a minutely cellular appearance with a central streak. The smaller and shorter 

 tentacles occupy as usual the edges of the posterior lobes, so that when the flaps 

 are adpressed they are close to the fissure leading to the mouth. As in P. hsematodes the 

 tentacles form an inextricable mass in a vessel, enclosing other annelids, fragments 

 of shells, Balani and mud. When much stretched, the tip, which is generally the 

 widest part, is yellowish, the attenuate region below it being pale, and the intermingling 

 of these hues, especially against a dark background, is striking. 



A specimen of moderate size can stretch its tentacles 3 or 4 inches, the processes 

 being dilated at the tip but of extreme tenuity toward the base, and the corpuscles 

 of the coelomic fluid are observed in the centre. Moreover, besides those in a straight 

 line many tentacles form curves, a coil or two or a series of coils like a corkscrew, and 

 then suddenly these are drawn rapidly towards the cephalic region as if they were 

 sliding along one of the attenuated tentacles in the line of retraction. By aid of these 

 organs the annelid pulls itself along the bottom of a vessel, its body meanwhile remaining 

 in various coils, and apparently taking no part in progression. Having reached the 

 corner of a glass vessel it seemed to be contented— keeping up a constant movement of 

 body and tentacles, apparently for respiratory purposes, the tail being frequently thrust 

 beyond the central mass as a finely tapered region with a slight swelling at the tip, whilst 

 waves of dilatation occured at intervals, and the numerous and closely arranged uncini- 

 gerous processes projected like lateral spines or serrations. In retracted tentacles the 

 grooves were evident. 



Instead of the single large first oral scute of P. medusa, this species has a tongue- 

 shaped median glandular process, the edges of which are free, and the anterior border 

 runs smoothly forward to the mouth. In one example this process was bifid posteriorly 

 whilst a small area was cut off anteriorly, the whole being symmetrical. It may represent 

 the first scute. 



The body resembles that of P. medusa, and like it is in the preparations almost 

 always coiled; only the tail is generally more tapered than in the species mentioned. 

 It is rounded dorsally and often dilated anteriorly, grooved ventrally, and terminatino- 

 posteriorly in the anus, which may have a simple crenate margin, though it generally 

 shows a more prominent ventral papilla, occasionally a smaller dorsal papilla or both 

 a dorsal and a ventral. Probably much depends on the condition of the region with 

 regard to reproduction. In the preparations dilatations occur dorsally both in the 

 region of the scutes, and, when this part is contracted, in the region behind. 



The ventral scutes commence with the large median tongue-shaped one already 

 mentioned, and laterally are two small scutes each of which abuts on a bristle- 

 process (first and second). Each of these has its inner edge bevelled by the 

 encroachment of the median scute. Six pairs of scutes follow, for the deep median 

 furrow separates the respective sides. A rounded glandular scute of small dimensions 

 is conspicuous on several of the succeeding segments, which have a longer antero- 

 posterior diameter than those in front. A glandular belt also envelops each bristle- 

 tuft anteriorly, and is continued, though less distinctly, posteriorly (Plate CXX, fig. 4), 

 where the uncinigerous processes are more evident than the setigerous. In the large 



