30 Proceedings of the Royal Physical Society, 
on a contractile stalk. Actinophrys, again, consists of a glo- 
bular mass of sarcode, in which may be distinguished two 
tissues : an internal one, which I shall call " endosarc," en- 
veloped by an external tissue, " ectosarc." The endosarc is 
dense, loaded with molecular matter and nutritive granules ; 
the ectosarc transparent, and produced into tentacular ap- 
pendages. Actinophrys has no mouth. Animalcules, seized 
by the tentacles, are drawn to the surface of the body, the 
soft sarcode of which becomes depressed, closes over them, and 
envelops them. They sink into the endosarc, and are ab- 
sorbed. The endosarc is the alimentary tissue; probably 
also the reproductive tissue. The ectosarc exercises the 
prehensile function. The tentacular processes of Actinophrys 
are homologous with those prehensile processes of the *' ec- 
toderm " which I have described as existing in several classes 
of aquatic animals, and to which 1 have given the term pal- 
pocils," a term which has lately been adopted by my friend Mr 
Gosse, in his interesting paper on Sarcodyction catenata. 
In Zooteirea, when expanded, the whole of the ectosarc is pro- 
longed into long and exceedingly attenuated palpocils, until the 
animal assumes the appearance of a globular brush of spun glass 
mounted on a transparent stalk. When irritated, the animal 
slowly contracts its stalk until the body is brought close to 
the surface on which it is attached, and the palpocils are con- 
tracted to a mass of little nodules (fig. 7, h). The stalk is homo- 
geneous, and is, as are the palpocils, a process of the ectosarc. 
A group of these animals form a very striking microscopic 
object when seen by the dark field illumination, — two cones or 
brushes of light appearing to issue from opposite sides of the 
body of each, and to pass round it in opposite directions when 
the mirror is moved. I have derived the name Zooteirea from 
Zma and rg/ggoc, a star^ or rather a constellation. 
3. Corethria SertularicB. (Figs. 8, 9, and 10.) 
This remarkable animal has occurred plentifully during the 
last few summers on the Sertularia pumila, which grows at 
low-water mark near Granton. I have only found it in one 
locality, at the extremity of the first ridge of rocks which 
runs out into the sea west of the long breakwater. Although 
