RHIZOPODA—FORAMINIFERA. 87 
Haliomma hexacanthum, figured from Miiller (Fig. 25), is an example 
of the ,Polycystina, in which the body is more or less encased in 
a siliceous shell ; while in the Thallasicollina the body is composed 
of aggregations of more or less fully differentiated cells, supported 
upon a framework of siliceous spicules, and thus obviously establishes 
a transition between typical Rhizopods and the Sponges. 
Before passing on to the Infusoria, a few words may he offered 
on the LVoctiluca, an organism certainly belonging to the Protozoa. 
One species only of this genus has been described, which 
occurs occasionally on the English coast in prodigious numbers, and 
_ 4s the chief cause of the diffused phosphorescence of our seas. 
It is a small creature, scarcely the hundredth part of an inch in 
diameter (Fig. 26, octiluca miliaris). It was discovered by 
M. Surriray, in 1810, who describes it as a spherical gelatinous mass, 
scarcely bigger than a pin’s head, 
with a long filiform tentacular ap- 
pendage, a mouth, an cesophagus, 
one or many stomachs, and 
branching ovaries—thus exhibiting 
a certain complexity of organisa- 
tion, pointing to affinities with the 
true Infusoria. De Blainville 
placed it among the Diphyde. 
Van Beneden and Doyére, on the 
other hand, deny its relation to the 
Acalephz, conceiving its organi- 
sation to be much more simple, 
and place it with the Rhizopoda. 
Quatrefages adopts the same view, denying the existence of a true 
mouth or intestinal canal: he considers the so-called stomachs as 
simple “ vacuoles,” similar to those observed in the Rhizopoda and 
Infusoria. Prof. Huxley, in the /ournal of Microscopical Science 
(vol. iii.), says it may be described as a gelatinous transparent body, 
about one-sixtieth of an inch in diameter and having very nearly the 
form of a peach, a filiform tentacle, equal in length to the diameter 
of the body, occupying the place where the stalk of the peach might 
be, which depends from it, and exhibits slow wavy motions when the 
creature is in full activity. ‘I have even seen a Noctiluca,” he adds, 
“appear to push against obstacles with this tentacle.” 
“The body,” he continues, “is composed of a structureless and 
somewhat dense external membrane, which is continued on to the 
Fig. 26.—Noctiluca miliaris (magnified). 
