340 DE. S. J. HICKSON — EEVISION OF THE 



Variety B, on the other hand, the ectoderm is highly vacuolated and its surface 

 irregular. The cells have branched processes which anastomose with one another, and 

 it is impossible to determine, in most cases, where one cell ends or another begins. 

 I believe that this vacuolated ectoderm is considerably stiflFer or firmer than the simple 

 columnar ectoderm of Variety A, and that it is formed for the support of the body- 

 wall in the absence of spicules. 



In Specimen 1 of this variety the stolon is thin and membranous, dividing into 

 ribbon-like pieces at the edges. The polypes are partially retracted and densely 

 crowded on the parts of the colony with a membranous stolon, but fully expanded and 

 widely separated from one another at the edges. 



The colour is brownish yellow, due to a considerable deposit of sand. 



The colony is parasitic on an Ascidian test. 



Specimens 2 and 3 are probably young examples of the above. The stolon is very 

 thin and composed of a number of anastomosing bands or ribbons. Most of the polypes 

 are fully expanded. They are both parasitic on mussel-shells. 



Locality. Coast of Victoria, shallow water. 



Clavulakia eamosa, Hickson (ii). (Plate L. figs. 9 & 10.) 



Stolon composed of a number of thin branching strands clinging to the branches of 

 a seaweed. The strands of the stolon are usually about h mm. in breadth, but never 

 exceed 1 mm. ; they do not fuse to form membranous or plate-like expansions. 



The polypes spring from the branches of the stolon singly at intervals of 3 mm. 

 The youngest polypes are found at the ends of the youngest branches. 



New polypes apparently never arise between the older polypes, but each polype is 

 formed in succession at the end of the growing branch of the stolon. 



The ramifications are formed by a simple bifurcation of the growing point of a 

 branch, and they are produced quite independently of the position of the youngest 

 polypes. Sometimes a polype may be seen springing from the angle of a bifurcation, 

 but more frequently there is no polype in this position. 



Judging from spirit-specimens only, the polypes are not capable of complete retrac- 

 tion into the branches of the stolon. In the retracted condition they are funnel- 

 shaped. The broad rounded distal extremity, 15 mm. in diameter, contains the 

 retracted calyx. The narrow proximal extremity at the point of attachment to the 

 stolon is '5 mm. in diameter. 



The distal extremity is marked by eight deep furrows. 



The spicules are numerous, both in the stolon and the polype-walls ; they are 

 double clubs O'l to O'lo mm. long. In the tentacles there are a few elongated lancet- 

 shaped spicules with iiTegular dentate projections (Plate L. fig. 11). 

 In spirit the specimens are dirty yellowish white in colour. 

 Locality. Coast of Victoria, shallow water. 



