184 ARTHUE DENDY. 



Heteropegma (fig. 20). 



In this genus we again go back to a Syconoid arrangement 

 of the caual system, though not a very typical one. In H. 

 uodus-gordii, the anatomy of which has been admirably 

 illustrated by Polejaeff (8), and of which I also venture to give 

 a drawing (fig. 20) based upon personal examination, the 

 sponge forms irregular agglomerations of small Syconoid 

 individuals, each with a single osculura and a central gastral 

 cavity. The flagellated chambers have extremely thin and 

 delicate walls, and branch in an extraordinarily copious and 

 irregular manner (fig. 20). The gastral cortex is also extremely 

 thin, but the dermal cortex is very strongly developed, and pene- 

 trated by irregular canals which lead from the inhalant pores 

 on the surface of the sponge into the quite irregular lacunar 

 system of spaces (''inter-canals^^) between the chambers. 



In Heteropegma latitubulata, which is found off 

 the south coast of the continent of Australia (H. nodus- 

 gordii being found off the north), we meet with an iden- 

 tical canal system and external form (4). The peculiarities 

 of the canal system in these, the only known species of the 

 genus, are brought about by the copious and irregular branching 

 of the chambers and the extremely slight development of the 

 mesoderm everywhere except in the dermal cortex. 



Amphoriscus. 



In this genus the caual system is more typically Syconoid, 

 such as we find in any of the Syconoid genera, like Grantia, 

 with a dermal cortex. As I have never myself met with the 

 genus, I may refer the reader to the account of Amphoriscus 

 (Sycilla) cyathiscus and A. (Sycilla) cylindrus given by 



Haeckel (5). 



Syculmis. 

 Here, again, the canal system appears to differ in no par- 

 ticular from the typical corticate Syconoid plan, like that of 

 Grantia. I must again refer the reader to Haeckel's great 

 work (6) for an account of the only known species (Syculmis 

 synapta). 



