834 
DE. J. S. BOWEEBANK ON THE ANATOMY 
the previously described forms ; the ordinary cruciform spiculum being converted into 
an external defensive one by the projection of a spicular ray from its centre. 
Dentato-cylindeo-hexeadiate (Plate XXXVI. fig. 39). — From a imique and very 
beautiful branching sponge from Nichol Bay, Australia, sent to me by Mr. Geoege 
Clifton, of Freemantle. The dentation of the radii of these spicula varies considerably 
in form and size ; the number of teeth at the apices of the rays is usually two or three, 
occasionally four, and very rarely five. The spicula are nearly uniform in size, and 
extremely abundant on all parts of the interstitial membranes. 
Extee-spinulated aecuate (Plate XXXVI. fig. 40). — From a small massive sponge 
from the Bahamas, presented to me by my friend Mr. M^Andeew. They are very 
abundantly dispersed over all parts of the interstitial membranes, are uniform in size, 
and vary to some extent in the degree of spinulation. In Part I. of this paper I 
described and figured a minute spiculum of the same "arcuate form (Phil. Trans. 1858, 
p, 322, Plate XXVI. fig. 51). I was not aware at that time from what part of the 
sponge it had been obtained. I have since found the same form abundantly dispersed 
on the interstitial membranes of a new species of sponge from Freemantle, sent to me 
by my friend Mr. Geoege Clifton. 
Spinulo-multifuecate hexeadiate stellate (Plate XXXVI. fig. 41). — This beautiful 
spiculum forms a connecting link between the spinulo-quadrifurcate hexradiate stellate 
form and the floricomo-stellate one, described and figured in the first part of this 
paper (Phil. Trans. 1858, p. 312, Plate XXVI. figs. 2, 3, 4). A careful examination 
of the specimen presents indications of there having been as many as eight secondary 
radii at the termination of the primary ray Avhich exhibits the greatest number of 
secondary ones in the figure ; and it is probable that this was the full complement of 
those parts. 
Multiangulateg ctlindeical (Plate XXXVI. fig. 42). — From a sponge in the British 
Museum. This spiculum had been accidentally included in the sponge. It is distinctly 
different from one of the same form described and figured in the first part of this paper, 
Phil. Trans. 1858, p. 314, Plate XXVI. fig. 10. It most probably belongs to the 
sarcode of a Geodia. 
Spinulo-multiangulated ctlindeical (Plate XXXVI. fig. 43). — Found among the 
extraneous spicula of the same sponge as the spiculum represented by fig. 42. This 
sponge is one of the Johnstonian Collection. It is designated Halichondria sanguinea, 
and its register is 47, 9, 7, 19. 
Inflato-aceeate, with inscissueate teeminations (Plate XXXVI. fig. 44). — From 
Hymerajghia verticillata^ Boweebanx, MS. A new species of British sponge from the 
Western Coast of Ireland. A terminal portion only of this spiculum is represented by 
the figure, the inscissurate character being the only novelty in the form. The inscissu- 
ration varies in degree to a considerable extent in different spicula, in some cases being 
very slightly produced, in others rather beyond that represented by fig. 44. The rudi- 
ments of a third ray are sometimes apparent. This form is an auxiliary skeleton- 
