RHIZOPODA FORAMINIFERA. 8/ 



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 be offered 

 on the Noctiluca, 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 

 is 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, Noctiluca 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 oesophagus, 

 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 Diphydce. 

 Van Beneden and Doyere, on the 

 other hand, deny its relation to the 

 Acalephae, conceiving its organi- 

 sation to be much more simple, Fig 26 - Noctiluca miliaris (magnified), 

 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 Journal of Microscopical Science 

 (vol. hi.), 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, 

 " a PP, ear to pusfr 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 



