Dr. Johnston on British Annelides. 5 
the orifice naked : segments numerous: branchie in the form of a 
globular tubercle over each foot, which is uniramous ; the briséles 
simple: ¢azl truncate, without styles. 
Oss. The relations of this genus are rather obscure. To 
Nephtys and Glycera it may be considered to approximate in the 
rudimentary state of the antennz, but in all other respects there 
is too great a dissimilarity to allow us to consider them as very 
nearly affined. The branchial tubercles over the feet might sug- 
gest a comparison with Phyllodoce, but there is no structural re- 
semblance ; the lamellz in Phyllodoce being merely modifications 
of the superior cirrus, moveable and jointed at the base, and 
acting as a kind of oar in the animal’s locomotion, while in Pol- 
licita they are branchial only, being immoveable, and of no use 
or applicability as locomotive organs. The difference in internal 
structure is equally great, for im the one genus the organ is 
veined with the ramifications of the blood-vessels, while in this 
it is very distinctly areolar. I have seen one species only, which 
may be named— 
1. P. Peripatus. Plate II. fig. 1—6. 
Hab. In deep water amid corallines, &c. Berwick bay. 
I have seen several Irish specimens in the collections of Mr. 
W. Thompson of Belfast. 
Desc. Worm about 2 inches long, very slender, narrowed to- 
wards both extremities, almost cylmdrical, of the usual yellowish- 
brown colour, roughish : head small, indistinctly separated from 
the following segment, longer than broad, rounded in front, 
where there are three unjointed antenna, the medial nearly as 
long as the lateral; on the sides of the head there are besides a 
few minute fleshy papill, and the feet advance on each side 
rather before the eyes, which are placed unusually backwards: 
eyes small, four, the anterior pair most approximate: mouth in- 
ferior : proboscis exsertile, large, smooth, emandibulate, the ori- 
fice plain: segments numerous, about the length of their own 
diameter, each of them furnished with a globose lamella or 
branchial tubercle on each side placed over and above the foot, 
immoyeable, unjointed, smooth, with a small papillary tip: feet 
about sixty pairs, one pair to every segment, conoid, uniramous, 
papillary, not projecting beyond the branchiz when at rest, but 
capable of being protruded beyond them, armed with four or five 
bristles and a spine; the Jdristles simple, sharp, curved like a 
hedge-knife, altogether retractile : the skin is covered with minute 
papille or granules, only visible under a high magnifier: anal seg- 
ment truncate, without styles, but on each side there is a mam- 
millary foot, which is larger than the penultimate, and, like it, 
appears to be destitute of bristles. 
