EEPOET ON THE POLYZOA. 
39 
The forms known to me as referable to the genus Cylindroecium as above defined 
are : — 
(1) Cylindroecium giganteum, Busk. 
Farrella gigantea, Bk., Quart. Journ. Micr. Sci., vol. iv. p. 93, pi. v. figs. 1, 2 ; Gosse, 
Mar. Zool., pt. ii. p. 22, fig. 40. 
Avenella gigantea, Hincks, Ann. and Mag. Nat. Hist., ser. 3, vol. ix. p. 473. 
Avenella fusca (forma producta), Smitt, Ivritisk Eorteckn., p. 503. 
Cylindrceciurn giganteum , Hincks, Brit. Mar. Polyz., p. 535, pi. lxxvii. figs. 3, 4. 
(2) Cylindroecium dilatatum, Hincks. 
Farrella clilatata, Hincks, Quart. Journ. Micr. Sci., vol. viii. p. 279, pL xxx. fig. 7. 
Avenella clilatata, Hincks, Ann. and Mag. Nat. Hist., ser. 3, vol. ix. p. 473. 
Cylindroecium dilatatum (pars), Hincks, Brit. Mar. Polyz., p. 536, pi. lxxix. figs. 1-3. 
(3) Cylindroecium fuscum, Busk. 
Farrella fusca, Bk., Quart. Journ. Micr. Sci., vol. iv. p. 94, pL vi. fig. 3. 
Avenella fusca, Alder, North. Cat., p. 69 ; 1 Norman, Shetland Polyz., Eep. Brit. Assoc., 
1868, p. 311 ; Smitt ( forma simplex), Kritisk Eorteckn., p. 503. 
Cylindroecium dilcdatum (pars), Hincks, Brit. Mar. Polyz., p. 537, pi. lxxvii. figs. 1, 2. 
(4) Cylindroecium pusillum, Hincks. 
Cylindroecium pusillum, Hincks, loc. cit., p. 537, pi. lxxx. fig. 8. 
(5) Cylindroecium pusillum, var. “dwarf,” Hincks. 
Cylindroecium pusillum, var. “ dwarf f Hincks, loc. cit., p. 538, pi. lxxx. fig. 9. 
(6) Cylindroecium papuense, n. sp. 
The respective dimensions of the zocecia in these species, so far as they can be made 
out (mostly from Mr. Hincks’s careful figures), are as follows, given in millimetres: — 
1. Cylindroecium giganteum, 
2. Cylindroecium dilatatum, 
3. Cylindroecium fuscum, . 
4. Cylindroecium pusillum, 
5. C ylindroecium pusillum, var., 
6. Cylindroecium papuense, 
Length. 
Breadth. 
3-5 
X 
(L20-0-25 
0-9 
X 
0-13 
1-7 
X 
0-2-0-3 
1-3 
X 
(H0-0-13 
0-7 
X 
04 
1-3 
X 
0-10--11 
From these dimensions it would seem that the form most nearly approaching that in 
the Challenger collection is the one named Cylindroecium pusillum by Mr. Hincks ; from 
this, however, it differs in the uniform diameter of the zocecia, which in the latter 
become wider or subventricose below. 
I may take this opportunity of remarking that the form named Farella fusca by me, 
from specimens collected at Newhaven, Firth of Forth, by Mr. W. Thompson in 1849, 
and which is considered by Mr. Hincks synonymous with his Cylindroecium dilatatum, 
