8 Porifera. 



they are cylindrical at the anterior pole the pigment appears. The larval A cells 

 are less fine than in Axinella, Reniera etc. Escape is through the osculum. - -In 

 Hircinia variabilis many layers of micromeres cover the macromeres, the free larva 

 is completely clothed with strongly developed flagellate epithelium ; cells, flagella 

 and nuclei being larger at the posterior pole. Cells of the inner mass are mostly 

 jB 2 . In metamorphosis they break through and grow over the flagellate A 

 cells; these sink in, not in one mass but in annular streaks; the groups to form 

 flagellate chambers have a linear appearance, canal-system developes in der be- 

 kanuten Weise . H o r n - f i b r e s : some connective cells bind themselves in wind- 

 ing strings, secreting between them a mass of horn ; they are JB 2 cells, analogous 

 to those which cement together spicules. Filaments were doubtfully identified 

 in non-staining, doubly-contoured spheres the size of a yolk-cell, appearing in 

 larva and young sponge, but not in the embryo; they are often pear-shaped. 

 - Spongilla. M.'s observations [Bericht f. 1890 Porif. p 5] require much cor- 

 rection : without doubt inversion of the layers takes place, but it is true that some 

 of the canal-system is formed in the free larva. Segmentation is really unequal. 

 The larval cavity is probably evolved from the structureless space in marine forms, 

 um den Uinfang der Larve wegen des Schwimmens im siiflen Wasser zu ver- 

 gro'Bern. - In sponges of different kinds watched from the larva one osculum 

 only appears except where there has been concrescence of larvae. - -A review of 

 existing embryological knowledge for sponges brings the following Conclusions. 

 If, which is uncertain, the two layers of larval sponges are comparable to those 

 of other groups, the flagellate cells are ectoderm and the large cells eutoderm. 

 The immigration of the flagellate cells differentiates them from all other Metazoa. 

 Sponges are not Coelenterates, embryology showing that the similarly placed 

 adult tissue-layers are not homologous. Probably in the ancestral sponge fixation 

 followed on a change in the method of nutrition, and spicules appeared as a sequel 

 to fixation. 



3. Anatomy etc. 



Names of species collected are recorded from Norway by Appellof and Norman. 



Hanitsch identifies Neusma Agassizi Goes, described as a Foraminifer [cf. 

 Bericht f. 1892 Protozoa p 13 as Stannophyllum zonarium, Haeckel , one of the 

 deep-sea Keratosa. Pearcey agrees that they probably belong to the same 

 group, this is not keratose Sponges. This conclusion is based upon the exami- 

 nation of nearly the whole Challenger collection: in not one species^ could be 

 found the slightest trace of any of the flagellated chambers characteristic of 

 sponges. Haeckel explains this by faulty preservation, yet he describes the 

 most delicate parts of a commensal Hydroid in full. If they prove true keratose 

 sponges we have no right to separate them from such genera as Masonella, 

 Syringammina , Technitella , Haliphysema . and Marsipella, now considered to 

 be Foraminifera and all forming siliceous and chitinous skeletons. Hanitsch 

 justifies Haeckel by the presence of oscula, pores, subdermal cavities, horny 

 skeleton , etc The chitinous lining in the tube-like body of some Fora- 

 minifera certainly bears not the slightest resemblance to the distinct fibrous 

 stroma of Stannophyllum , which more recalls the filaments of Hircinia; its con- 

 centric lines are the only feature suggesting a Foraminifer. 



Levinsen's report (Danish) on the sponges of the Hauchs expedition com- 

 mences with a practical synopsis for determination of 26 Danish species, grouped 

 again for description under Chondrosidae, Halisarcidae , Suberitidae, Desmacido- 

 nidae, Spongelidae, Asconidae, and Syconidae. Locality and generally depth and 



