STHENELAIS ZETLANDICA. 497 
ventral bristles, so that the type is conserved, though, as Mr. Southern observes, the view 
of Ehlers that the dorsal bristle has lost its terminal piece is not tenable. 
Southern agrees with Ehlers that Pregeria most nearly approaches the Aphroditide, 
resembling the Sigalionidee “in the reduction of the head and its appendages, the forward 
position of the buccal segment, the shape of the compound sete, and the presence of jaws.” 
“T am of opinion that the elongate ventral anterior cirri of the Pisionidee are homologous to 
the palps of the Sigalionins, that the slender dorsal and globular median cirri, together 
with the swollen bases, which contain the prominent spines, constitute the parapodia and 
cirri of the buccal segment, the whole being homologous to the segment bearing tentacular 
cirri in Pholoé, and the first setigerous segment in Sthenelais. The first setigerous segment 
in the Pisionidee would then be homologous to the first setigerous segment in Pholoé and 
to the second in Sthenelais. In all three cases the ventral cirrus of this segment is elongate 
and functions as a tentacular cirrus—-a remarkable resemblance, which is best explained by 
the theory of close relationship.” 
Whilst these views are full of interest, it has to be added that no known Sigalionid, or 
other allied form, shows anything approaching the condition in the cephalic region of Prageria 
with its remarkable spines, though the proboscis, its circlet of papillae and its jaws have 
a near resemblance to those in the Polynoide and allied forms. The length of the feet and 
the proportionally great size of the bristles, which stretch far inward into the tissues of the 
body, are more in consonance with a pelagic habit than are the bristles and feet of the Siga- 
lionide. Further, the bristles themselves have a closer approach to those of the Syllids 
than to any other group, even to the serrations on the enlarged distal region of the curved 
shafts. The simple condition of the dorsal bristle is akin to that observed in Syllis spon- 
gicola and S. gracilis, whilst even a more complex arrangement is seen in Ancistrosyllis 
graenlandica. On the other hand, the presence of teeth diverges from anything at present 
known in the Syllids—even from the condition in the parasitic Syllis on the eel. 
Faminy SIGALIONDA. 
STHENELAIS ZETLANDICA, Mcl. 
Additional particulars have been obtained by Mr. Southern, who found a complete 
example. The head is oval, and bears two pairs of kidney-shaped eyes; median tentacle 
with a basal joint, and on each side is a short, rounded cephalic ctenidium. Palps long 
and tapered. The first feet project in front of the head, and its ctenidium is near the base 
dorsally. On the inner margin is the lateral tentacle. Setigerous lobe bears long, slender, 
dorsal and ventral cirri, and between them the buccal ctenidium—a delicate membrane. A 
single spine and two fascicles of simple, serrate bristles alone are present. The second 
feet project laterally; some of the ventral sete are long and slender, and the terminal pieces 
have from seven to eight articulations. In the succeeding feet these bristles grow shorter, 
so that at the fifth two or three articulations only are present in the tips. The dorsal simple 
setae are bifid at the tip in Irish specimens, according to Southern, but this unusual feature 
in a Sigalionid is absent from the original incomplete example. The ventral cirri of the 
second feet are longer than those which follow, and are nearer the median line; and the 
224. 
