798 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Development of Reniera filigrana.* — W. Marshall is led by his 

 studies on this sponge to the conclusion that the Spongias represent 

 a very old branch of the Coelenterate stem, in which, in consequence 

 of later adaptations and compressions, we have but a scanty phylo- 

 genetic history. Attention is directed to the view of Leuckart that 

 the Porifera have a relation to the Coelenterata in consequence of 

 the homology of the ciliated cavity of the simple calcareous sponge 

 (Grantia), with the body-cavity of a hydroid polyp, the mouth-orifices 

 also correspond, and the pores of sponges are comparable to the 

 water-spaces of the Coelenterata. On the other hand, Balfour has 

 insisted on the striking peculiarities of the sponge-larvae, the early 

 development of the mesoblast, and the remarkable characters of the 

 digestive canals, as evidence in favour of the independent origin of the 

 Poriferous phylum. To this Marshall answers tbat the larval 

 peculiarities are chiefly to be seen in the Calcispongise, while the 

 FibrospongiaB have much more similarity to certain higher Ccelenterates 

 (e. g. Eucope). The sessile condition of the sponges may be supposed 

 to have conditioned the development of a skeleton, and this may be 

 taken to be one of the causes of the marked development of the 

 mesoderm. The entrance of the water-pores into the service of the 

 digestive organs is looked upon as due to a change in function, which 

 has again necessitated a greater development of the mesodermal 

 tissues. It is next pointed out that in both groups we see a centri- 

 fugal canal system differentiated from the gastric cavity, which often 

 breaks through the ectoderm and communicates with the exterior by 

 permanent or inconstant pores ; where there are tentacles present the 

 canals or a part of them may be developed therein, and in some cases 

 the pores opening from them to the exterior become so well developed 

 that an astomatous condition is set up. In addition to this, the 

 author believes that the ciliated investment of the tubes is derived 

 from the endoderm layer. As to the absence of tentacles and stinging 

 cells, attention is directed to the absence of both these organs from 

 Beroe, and to the probability of their being nothing but the results of 

 adaptation in the true Coelenterata ; while, further, their absence in 

 sponges is to be explained by the present mode of nutrition exhibited 

 by these forms. 



Sponges and Coelenterates are, then, Metazoa with gastric cavities 

 and mesenterial pouches, with centrifugal canals arising from the 

 former which may open to the exterior by pores and take in nutriment ; 

 they are invested by endodermal cells, which may become converted 

 into flagellate cells. They are both developed from a common Prot- 

 adinian stem-form. 



New Fresh-water Sponges. — Mr. H. J. Carter describes f a new 

 species of Spongilla from Bombay (S. bombmjensis) of which only the 

 statoblasts have been found. The most characteristic part of this 

 species is, that the chitinous coat is spiculiferous, and that when the 

 statoblast is divided through the middle or the outer layer crushed, 



* Zeitschr. f. wiss. Zool., xxxvii. (1S82) pp. 221-46 (2 pis.), 

 t Ann. and Mag. Nat. Hist., x. (1882) pp. 362-72 (1 pi.). 



