ICf THE VOYAGE OF H.M.S. CHALLENGER. 



seems to differ so mucli in its comparative dimensions) as perkaps l^o 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. ENTOPEOCTA, 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. 



Folypiaria pedicellinea, Gevfsls, 1837 . 



Pedicellinx, Jolinst. 



FedicelUnuix, 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^ 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, 

 suoh 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 

 ceUs. 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 lamioa 



> Brit. Mar. Polyz., vol. i. p. 563. 



