ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
209 
having been found. The discovery of Diphasia fallax in the south of 
Ireland gives this species a much wider southern range than has hitherto 
been assigned to it. 
Australian Hydroids.* — Mr. W. W. Bale has some further notes, 
chiefly on specimens collected at Port Phillip ; nine, inclusive of Prof. 
Spencer’s Plumularia procumbens and Clathrozoon wilsoni , were found to 
be new. The genus Halocordyle , not hitherto known to occur in Australia, 
was represented by a single specimen. The author thinks that the 
presence of a secondary envelope in Diplocheilus mirabilis is illusory, 
and that the genus should be sunk in Kirchenpaueria. 
Porifera. 
Development of Cornacuspongise.t — Dr. O. Maas has an important 
paper on the development and metamorphosis of Cornacuspongias. The 
first part of his memoir describes the metamorphosis of Axinella crista- 
galli sp. n., the development of the larva of Myxilla rosacea 0. S., the 
metamorphosis of the larva of Gellius varius Bwk., the development of 
the larva of Chalinula fertilis , and includes notes on the development 
of the horny sponges ( Hircinia variabilis and Euspongia officinalis) and of 
Spongilla. 
It will be more profitable to restrict our attention to the general 
results. Dr. Maas is quite convinced that the Sponges are true Metazoa, 
probably descended from diploblastic ancestors, but they are markedly 
divergent in that the flagellate locomotor cells of the embryo come to 
lie internally. The Sponges are in no case Coelentera, for their layers 
are not homologous with the inner and outer layers of Coelentera, and 
their canal system is absolutely divergent, as also is the differentiation 
of the tissues after sedentary life begins. 
The more we know of sponges, the more variety is discovered in 
their ontogeny, as is perhaps not unnatural in so primitive a phylum. 
Apart from the larvae of the horny sponges and Spongillidae which are 
completely flagellate, the Cornacuspongiae show two types of larva, 
which in no case have flagella at the posterior pole. In Esperia, Myxilla , 
Desmacidon , Clathria , Dictyonella , and Axinella , the flagellate cells simply 
stop towards the posterior end ; in Beniera, Chalinula , Gellius, Pachy- 
chalina , and Toxochalina the flagellate cells end in a distinct ring of large 
cells with large flagella. There are also characteristic differences of 
pigmentation between the two types. It is supposed that in the com- 
pletely flagellate larvae, apparently not heteropolar like the rest, the 
flagellate annulus of the second type has simply been extended 
backwards. 
After considering such difficult cases as that of Sycandra, and comparing 
the development of Sponges with that of Coelentera and other Metazoa, 
Maas comes to the conclusion that one must choose between denying all 
homology between the germinal layers of sponges and those of other 
animals, and regarding the flagellate cells as representing the ectoderm 
and the large cells the endoderm. He regards the formation of the two 
* Proc. Roy. Soc. Victoria, 1893, pp. 93-117 (4 pis.), 
t Zool. Jahrb. (Abth. Anat. Ontog.), vii. (1893) pp. 331-448 (5 pis.). 
