300 A MONOGRAPH OF THE AUSTRALIAN SPONGES, 



Histology. 



I have not observed an}- thing peculiar in the structure of this 

 sponge. It is remarkable, that no granules are found in the 

 ground substance ai'ound the ciliated chambers. It is known to 

 the readei', that the family of the Spongidae has been defined as 

 comprising species with such granules by F. E. Schulze (1) a 

 definition accepted by us afterwards without alteration. If I now 

 place these sponges in this family ; I do so in consequence of a 

 desire on my part not to complicate the classificatory system too 

 much ; and not because I think that the presence or absence of 

 granules is a thing of little importance. I must however say that I 

 examined several, as yet undescribed species of horny sponges 

 which I intend to describe as Spongidaj, which likewise possess a 

 comparatively clear ground substance. 



The tenacity with which such peculiarities adhere to certain forms 

 — the "systematic value " of them — can as yet not be ascertained 

 because we know so very little about all these sponges. 



I have found both male and female sexual products in the 

 specimens I have examined but I cannot say whether the species 

 is hermophroditic or not. I have never found male and female 

 sexual cells side by side, but this of course is an observation of no 

 value to decide this question. 



Parasitic Alg^e in the Skin. 



In the outer skin between the hard sandy cortex and the outer 

 surface generally, small algse are met with, which have the shape 

 of tine threads consisting of a string of cells. (Plate XXVIII., 

 fig. 10.) These threads are rounded on each end. 



It is connected with difficulty to find these structures, because 

 they are of a very faint brown color and very small. I have 

 however, been able to find them in most specimens, and I cannot 

 say whether they do not occur also in those where I have not seen 



(1 ) i''. E. Schnke. Untersuchungen Ueber den Bau unci die Entwickelung 

 der Spongien Die Familie der Spongidre. Zeitschrift fiir wissenschaftliche 

 Zoologie. Band XXXII. 



