40 
THE VOYAGE OE H.M.S. CHALLENGER. 
seems to differ so much in its comparative dimensions as perhaps to deserve recognition 
as a distinct species, which might be named Cylindrcecium fuscum, as being the first of 
the genus to which that appellative was given. 
Group B. ENTOPROCTA, Nitsche. 
Entoproda, Nitsche, Zeitschr. f. wiss. Zool., Bd. xx. p. 34; Hincks, Brit. Mar. Polyz., p. 563. 
Character . — Both oral and anal orifices lying within the crown of tentacles ; no 
tentacular sheath. Tentacles contractile but not retractile, arranged bilaterally and 
symmetrically. 
Order PEDICELLINEA. 
The only order. 
Family I. Pedicellinid^®;, Hincks. 
Polyjoiaria pedicellinea, Gervais, 1837. 
Pedicelline e, Johnst. 
Pedicellinidx, Smitt, 1867 ; Hincks, 1880; Jullien, 1885 
Character . — Polypides deciduous, borne on a more or less muscular, rigid or 
contractile peduncle ; united into colonies by a chitinous ramified stem or stolon. 
The general characters of the family Pedicellinidse are so well and succinctly given 
by Mr. Hincks 1 as scarcely to require further observation. The chief points to be 
noticed, as he remarks, besides the Entoproctous anal orifice are — 
1. That there is no invagination of the anterior region and therefore no tentacular 
sheath, and consequently an absence of the retractor muscular fibres by which it is 
retracted in the Ectoproctse. 
2. That the integument is soft and never calcified, and is closely applied to its 
contents ; i.e., there is no perivisceral cavity containing a fluid as in most other Polyzoa, 
such small space as there is between the inner wall of the calyx and the contained 
organs is occupied by a more or less delicate parenchymatous tissue. The integument is 
composed of a very delicate outer membrane lined by a layer of flattened polygonal 
cells. The outer membrane or ectocyst is prolonged beyond the visceral mass and forms 
the side of the vestibular cup-like chamber, within the transparent walls of which the 
tentacles are usually seen coiled. The tentacles arise from the upper edge of the inner 
surface of this cup, and their outer surface is formed by a prolongation of the transparent 
ectocyst, whilst the inner is covered by a more opaque layer of ciliated cells. The 
vestibular chamber is separated from the visceral part of the polypide by a thin lamina 
1 Brit. Mar. Polyz., vol. i. p. 563. 
