About half an inch high. The stem becomes thicker as it ascends, and divides into two equal short branches, each of which again subdivides into two short truncate branches, in a plane at right angles to the primary division. The cells in the upper part of the stem appear free for nearly half their length, and are gently curved outwards. The surface is covered with pretty regularly and quincuncially arranged minute papillae, the apex of each of which is flattened or rounded, and of a dark brown or black colour. The mode of subdivision of the polyzoary, and the truncated ends of the branches, and the more numerous cells, suffice to distinguish this species from P. proboscidea. The cells in the figure of P. deflexa appear to be much more slender in proportion, and the branches in that species are not truncated, but attenuated at the extremity.
3. IDMONEA, Lamouroux.
1. I. radians, M. Edwards. Ann. de Sc. N. tome 9 page 25 plate 12 figure 4.
Retepora radians, Lamarck.
Habitat: Bass Strait, 45 fathoms.
One minute specimen, but very perfect, has been examined; but it is undoubtedly the one described and figured by M. Edwards, and noticed by Lamarck as inhabiting the seas of New Holland. M. Edwards' doubt therefore as to this locality is now removed.
Fam. 2. CRISIADAE.
4. CRISIA, Lamouroux.
1. C. denticulata, Fleming.
Habitat: Bass Strait, 45 fathoms.
Parasitic upon a species of Salicornaria. The only difference, if there be any, between this form and the British, consists in the rather greater projection or freedom of the extremities of the cells, which are curved towards the front.
2. C. acropora, n. sp.
Cells 9 to 13 in each internode; lateral branches given off between the first and second, or between the second and third cells above a joint. A small conical tooth, sometimes bifid, above and behind the mouth.