REPORT ON THE CRINOIDEA. 369 
in the tabular key to the species which embraces all the types of this genus that have yet 
been discovered. 
The individual described above is the only specimen of any kind of Crinoid which was 
obtained at Station 209; and it has fortunately suffered much less injury than many of 
the larger types dredged by the Challenger. I did not succeed in finding any Myzostoma 
upon it; but a Scalpellwm is attached to its stem, and several individuals of Verruca to 
the cirri, on one of which a small Avicula was fixed by its byssus. 
11. Metacrinus tuberosus, n. sp. (Pl. LIII. figs. 1-6). 
Three species (Metacrinus angulatus, Metacrinus nobilis, Metacrinus cingulatus), repre- 
were dredged by the Challenger at Station 192, off 
the Ki Islands. Together with these there came up a fragment of a stem which I cannot 
1 
sented by “about a dozen individuals, 
refer to either of these species, nor to any other Metacrinus yet known. It presents a 
curious combination of certain features which are characteristic of the stems of Metacrinus. 
angulatus, Metacrinus costatus, and Metacrinus nobilis respectively, three very distinct 
species from widely separated localities on different sides of the equator (Ki, Meangis, 
and Kermadec Islands). I have no hesitation in regarding it as belonging to another 
species of the genus, although the characters of its calyx are as yet unknown. 
It cannot belong to a Pentacrinus on account of the upward extension of the cirrus- 
sockets on to the supra-nodal joints (PI. LIII. fig. 2), a character which is eminently 
distinctive of Metacrinus. 
The fragment consisted of five complete internodes, one of which was sacrificed to 
anatomical purposes, so that only four are shown in the figure (Pl. LUI. fig. 1). Hach 
internode consists of seven slightly crenulated joints. The five middle ones are as usual 
different from those immediately above and below the nodes. They are sharply 
pentagonal in form, with a somewhat prominent tubercle in the middle of each side 
(Pl. LIII. figs. 4, 6); while the angles are sharp and slightly produced outwards beyond 
the ends of the petaloid areas, as is to some extent the case in Metacrinus angulatus and 
Metacrinus costatus (Pl. XXXIX. figs. 3, 8,10, 11; Pl. XLIX. figs. 3, 4). This is still 
more evident in the nodal joints (Pl. LIII. fig. 3) as it also is in the other two species 
(Pl. XXXIX. figs. 3-5; Pl. XLIX. fig. 5), and more distinctly in Metacrinus nodosus, 
the internodes of which are not specially produced at the angles (PI. LI. figs. 8-10). 
The consequence is that the stem of Metacrinus tuberosus, like that of Metacrinus 
angulatus and Metacrinus costatus, is traversed by prominent interradial ridges 
(Pl, XCXVIE EPOX XMIX. figs, 3) 00: PES RLIX. figs. 1,.3; PL. DIT figs. 196). 
The nodal joimts have somewhat deeply hollowed cirrus-sockets which have relatively 
wide facets, and encroach both on the supra- (Pl. LIII. fig. 2) and on the infra-nodal 
1 See R. v. Willemoes Suhm, Briefe von der Challenger Expedition, No. iv., Zeitschr. f. wiss. Zool., Bd. xvi. p. liil., 
1876. 
(ZOOL. CHALL, EXP.— PART XxxIt.—1884.) Ii 47 
