the Trondhjem Fiord. 449 
2 millim. in diameter at the base, and thence tapers gently to 
the summit, where it is half that diameter. When living 
the stem is cylindrical and vertical, so that the crown of 
branches is held at its height above the mud; but when dead 
all efforts to preserve it in its natural form failed and the sides 
entirely collapsed, and it is thus evident that the stem is com- 
posed of a very delicate smooth surrounding membrane, filled 
with fluid; the fluid must escape, I think, at the top of the 
stem between the bases of the branches, as I cannot find any 
rupture in the side-walls. Delicate as the membrane which 
forms the stem is, it is of considerable strength; the stem 
may be bent in any number of folds, it will not break. At 
the summit of the stem this membrane expands and invests 
the base of the crown, extending a little distance up the 
branches, on the sides of which it is extended as a thin film. 
The crown is about 2 inch high, and is composed of dicho- 
tomously dividing flexible branches. 
The zocecia viewed from above (Pl. XIX. fig. 3) have the 
lateral margin straight, without any sinus, and the terminal 
spine-point is small “and does not rise above the slightly pro- 
jected anterior margin of the zocecium ; viewed laterally (fig. 4) 
the dorsal margin js seen to be straight or only very slightly 
arcuate. The avicularia (fig. 5) are greatly elongated and 
at the base the point of attachment is extremely fine; they 
spring from the delicate lateral margin of the zocecium about 
or a little above the middle, and are so long that they project 
when directed forwards considerably beyond the summit of 
the zocecium, sometimes by the whole length of the mandible. 
B. Kinekoskias cyathus (Wyville-Thomson). (Pl. XIX. 
figs. 6-8.) 
1877. Naresia cyathus, Voyage of the ‘Challenger, The Atlantic, 
p. 142, and woodcut. 
1881. Bugula (Kinekoskias) cyathus, Busk, Quart. Journ. Mier. Sci. n.s. 
vol. xxi. p. 1, pl. i. figs. 1, 3, 4. 
1884, Kinekoskias cyathus, Busk, Report ‘Challenger’ Polyzoa, The 
Cheilostomata, p. 44, pl. vill. figs. 1 and 1 a-c. 
Judging from the figures given, as well as from the frage- 
ment which I have had the opportunity of examining, this 
species is much less flexible and more charged with calcareous 
matter than the last. Hence its crown, which. is also con- 
siderably larger than that of A. Smité¢ in relation to the 
height of the stem, stands up more stiffly. But be that as it 
may, the following points afford good specific characters. 
The zocecium seen from above (Pl. XIX. fig. 6) has the outer 
margin flexuous ; at a short distance from the base it suddenly 
Ann. & Mag. N. Hist. Ser. 6. Vol. xii. 34 
