STUDIES ON THE COMPARATIVE ANATOMY OF SPONGES. 181 



Leucyssa. 

 This genus also appears, from the very scanty information 

 which we possess with regard to the canal system (5), to con- 

 form to the ordinary Leuconoid type. 



Grantessa (fig. 18). 



In this genus we find ourselves returning to a canal system 

 which is emphatically Syconoid, and agrees closely with that 

 which we have already described in the genus Grantia. This 

 will be rendered obvious by a comparison of fig. 18, represent- 

 ing a portion of a transverse section of Grantessa intusar- 

 ticulata with fig 9, representing a similar section of Grantia 

 extusarticulata. In Grantessa sacca, one of the most 

 beautiful of our Australian sponges, the chambers are very 

 long and copiously branched (4). All the known species are 

 solitary Syconoid individuals or branching colonies, never 

 completely fused into solid, massive forms. In Grantessa 

 erinaceus we meet with a very striking peculiarity, in the 

 presence of ingrowths of mesoderm from the gastral cortex, 

 covered by a single layer of flattened epithelium, into the gastral 

 cavity. These ingrowths form a series of irregular ''endogastric 

 septa" without any spicules. They are present in both the speci- 

 mens in my possession, and, as Mr. Carter also mentions them 

 (12), they would seem to be constant in the species. In G. 

 erinaceus also, the flagellated chambers are very irregular and 

 much branched, and they communicate with the gastral cavity by 

 unusually long exhalant canals, which unite together in groups. 



The anatomy of Grantessa (A mphoriscus) poculum 

 has been figured by Polejaeff" (8) and re-investigated by myself. 

 The canal system of this species agrees closely with that of G. 

 intusarticulata (fig. 18). 



Heteropia. 

 The only species which I propose to retain in this genus is 

 Carter's Aphroceras ramosa (15), which appears to have a 

 typical radiate Syconoid canal system, complicated only by 

 the development of a strong dermal cortex resembling that of 

 tlie genus Ute. 



