170 ARTHUR DENDY. 



dermal membrane stretched across the openings^ which are so 

 narrow that such a structure could hardly be required. 



In Sycon Ramsayi, a species common in Port Jackson 

 and described by von Lendenfeld (11), the exhalant canals, 

 though confined within the limits of the thick gastral cortex, 

 are extraordinarily well-defined cylindrical tubes, and it is 

 interesting to notice that although the long radial chambers 

 are themselves unbranched, and there is no indication of the 

 exhalant canals having been formed by modification of their 

 proximal ends, yet these canals may unite together before 

 opening on to the gastral surface, and thus present a branching 

 structure. In other respects Sycon Ramsayi agrees in canal 

 system with the simpler species of the genus. 



Sycantha. 



We owe our information concerning this sponge entirely to 

 von Lendenfeld, who has recently described it from the Gulf 

 of Trieste, and from his work (10) the following details as 

 to the canal system are taken. 



Sycantha teuella (the only species) is a large, tubular 

 sponge, with a single terminal osculum. The gastral cortex is 

 thin, and forms a cylindrical tube. From the outer surface of 

 the gastral cortex project tufts, which are partially united 

 together by membranes, and attain a length of 2 — 4 mm. 

 Each tuft runs out into a number of flexible points. These 

 points are the free distal ends of the flagellated chambers of 

 which the tufts are composed. Ten to twenty chambers, 

 united at their bases, form a tuft, each of which is thus a 

 group of flagellated chambers. The chambers themselves are 

 long and narrow. At the base they are irregularly prismatic, 

 generally quadrangular in cross-section. The free, always 

 unbranched, terminal portion is circular in cross-section, and 

 runs out into a conical point. In their basal portions the 

 chambers touch one another, and here there are no inhalant 

 canals (inter-canals) between them, so that collared cells are 

 found on both sides of all membranes which occur in the 

 interior of the basal portions of the tufts. In these membranes, 



