REPORT ON THE HOLOTHURIOIDEA. 
45 
plates, with numerous holes and a central crown built up of three rods. Colour in 
alcohol, whitish. Length of the largest specimen about 90 mm. 
Habitat. — Station 45, Ma}’ 3, 1873; lat. 38° 34' N., long. 72° 10' W.; depth, 1240 
fathoms; bottom temperature, 37 ’2; blue mud ; four specimens. 
The posterior very narrow part of the caudal portion of the body is always broken off 
in all the individuals I have had at my disposal, but in the same bottle where they are 
kept, some caudal portions are left, probably belonging to the animals in question. Tliey 
are about 30 mm. long, so that the largest specimen must be considerably longer than 
above noted, if one of these parts really belong to it. The anal aperture is surrounded Ijy 
five calcareous teeth and a number of minute papillae, the latter being disposed in a ring 
exteriorly and around the former. As in Haplodactyla, Anhjroderina, &c., no retractor 
muscles are present. The longitudinal muscular bands are divided throughout their 
w’hole length. The calcareous ring consists of ten pieces which are so united as to 
constitute a continuous w’hole ; each radial piece is marked anteriorly by two shorter 
processes and posteriorly by a large bifid projection ; the interradial pieces only possess 
a single shorter process in their anterior margin. Polian vesicle as well as the madre- 
poric canal single. The respiratory-trees are two in number, with short branches ; in one 
of the individuals the left tree is divided near its base into two parts. The genital tubes 
numerous, slender, and very narrow. 
The calcareous deposits of the integuments are numerous, and especially in the 
caudal portion closely crowded. In most cases they present a somewhat triangular form, 
with three, seldom four, central holes larger than the remaining ones. The largest plates 
measure as much as 0'2 mm. in diameter. From the centre a crown rises, composed of 
three, seldom four, rods which become connected with one another by several cross-rails and 
terminate in several processes. The basal parts of these rods constitute the three or four 
central holes just mentioned, wherefore the plates, when the crown is broken off at the 
base, present a single large hole in their centre. The five teeth round the anus are 
formed by a firm calcareous network, and they seem to be provided wdth two rather long 
roots, by means of which they are firmly attached to the body-wall. According to 
Brandt,^ the genus Liosoma as wnll as its species Liosoma sitchaense is characterised by 
having twelve peltate tentacles, and in 1857 Stimpson^ describes another form, Liosoma 
arenicola, with fifteen tentacles composed of a short peduncle with four or five digita- 
tions at the disk-like .summit ; these branches being also minutely pinnate towards their 
extremities. No deposits are known from the integument of the two forms just 
mentioned. Thus the form of the tentacles should be the only characteristic of 
importance distinguishing Liosoma from, for instance, Haplodactyla, Trochostoma , and 
' Prodromus, &c., 1835, p. 58. 
^ On the Crustacea and Echinodermata of the Pacific Shores of North America, Journ. Boston Soc. Nat. Hist., vol. vi. 
1857, pp. 85, 86 (extract). 
