470 ASTROSCLERA WILLEYAXA, THE TYPE OF A NEW FAMILY OF SPONGES. 



All I can say is that in the material, preserved as it has been, the condition appears 

 to be as I have described. 



Canal System. The large trunks of the canal system and the small branches 

 which ramify in the layer of tissue containing ciliated chambers have nuclei scattered 

 uniformly in their walls (Fig. 12, canal to right, and Fig. 14, c), but I have not suc- 

 ceeded in recomising cell limits about them. 



Most of the skeletal canals are lined by tissue containing ciliated chambers in 

 abundance, though in some rare instances, as in the left-hand canal represented in 

 Fig. 12, the lining contains no ciliated chambers. It may be that these are efferent 

 passages, but I have not succeeded in recognising in the Lifu specimens, (which alone 

 contain the soft tissues,) a clearly differentiated system of large canals corresponding to 

 those seen in the Funafuti specimen. 



The existence of ciliated chambers implies the presence of systems of afferent and 

 efferent canals ; and as a matter of fact we find that the tissue containing the ciliated 

 chambers is traversed by trunks which give off small branches into the tissue. Of the 

 small branches seen in the tissue some may well be tributaries of the efferent system 

 of canals. 



It appears that in this young stage at least, the main trunks of the efferent 

 system are in many cases also surrounded by tissue containing ciliated chambers, 

 together with efferent tributaries and the ultimate branches of the afferent sj-stem, so 

 that in sections of the soft parts the two systems of canals are not recognisable by 

 their anatomical characters. 



Reproduction. Each of the tliree specimens examined contained large eggs or 

 embryos (Figs. S, 9 and 10). They are found, solitary or two together, near the orifice 

 of one of the larger canals, separated from the skeletal wall by a thin layer of soft 

 tissue. I have not been able to recognise eggs in a young stage. An advanced ovum 

 in one specimen (Fig. 9) measures O'l mm. in length, and has a thick-walled nucleus 

 25/i in diameter, and a well-marked germinal spot. An embryo in the same specimen 

 (Fig. 10) is rather larger than the egg. At the surface there is a superficial layer of 

 nuclei, and the protoplasm about them is disposed in columns perpendicular to it. 

 Internally the columns are merged in the granular protoplasm, which occupies the 

 interior of the embryo, obscurely divided up into irregular masses, but I have not 

 succeeded in detecting nuclei in them. None of the embryos have a segmentation 

 cavity. It appears that the development leads to the formation of a larva of a 

 parenchymula type, rather than an ainphihlastula. 



I have not been able to recognise any stage in the formation of spermatozoa. 



State of Preservation. The three specimens whose soft parts have been examined 

 do not show the structure equally well. The above description is given from the 

 Lifu specimen which was prepared by von Koch's method, and of which part was 

 cut into sections 5/i in thickness. In another specimen the reticular character 

 of the soft tissue is clearly seen, but the fiagella of the ciliated chambers are 

 obscure. This is partly due to the fact that the sections are in .this case considerably 



