52 
THE VOYAGE OF H.M.S. CHALLENGEE. 
tables composed of an irregular two- or three-armed network representing the 
disk and carrying a central slightly spinous process. 
Habitat . — Kerguelen Island (Studer). 
The species mainly differs from the preceding ones in the very large, fusiform or 
three-armed deposits without spires, present all over the body though in larger 
numbers at its extremities. 
Trochostoma turgidum (Molpadia), Verrill, 1879. 
Tentacles two-lobed. Deposits — round or oval orange-brown bodies of a concentric 
structure ; large irregular table-shaped plates consisting of a perforated disk with 
a central circle of three to six holes and an outer of ten or more larger oval 
holes, and a central spire built up of three to four columns. 
Habitat . — Southern coast of New England, Fundy Bay, Massachusetts Bay, Gulf of 
Maine, Casco Bay; off Nova Scotia, Gulf of St. Lawrence (Verrill). 
Verrill does not mention anything about anal papillae. From the description it is 
impossible to understand what is the meaning of “ with two-lobed tentacles,” 
either there reaUy are only two digits or the two lobes are situated below 
the top of the tentacles, in which case the tentacles are three-lobed as in the 
preceding species. ■ Possibly the species is identical with Trochostoma boreale, 
Sars, which is distinguished mainly by its tables being much more irregular and 
smaller. 
B. Deposits — ^tables alone, 
Trochostoma arcticum {Haplodactyla), yoxi Marenzeller, 1878; Danielssen and Keren, 
■ 1879, 1882. 
Tentacles with five to seven digits ; in young only three digits. Tables almost like 
those in Trochostoma boreale. 
Hahitat . — Finmark (Danielssen and Koren), north of Nova Zembla (von Marenzeller). 
(Mus. Holm.) One specimen from the Kara Sea. The tables consist of a very 
irregular disk and a short spire. The disk consists of longer or shorter, branched 
or simple arms, running out irregularly from a common centre ; these arms are 
either united with each other so as to form a disk with a few large holes, or 
they remain free, thus constituting a disk resembling a branched spicule. The 
spire consists of a simple shorter central rod, which often terminates in a few 
spines. Towards the extremities of the body the tables change their shape, 
their disk being elongate, more like true disks, and provided with more holes, 
and their spire being composed of about three rods intimately united with each 
other, so that the spire often gives the impression of being a simple column ; the 
top of the spire terminates in several teeth. 
