490 AUSTRALIAN FRESHWATER POLYZOA, I., 



in place of AUman's " bean-shaped." No statoblasts, however^ 

 which I have examined, resemble those shown by Allman, as 

 representing these structures in F. sultana] and what variation, 

 has been noted has been very slight in any wa}^ approaching 

 those of F. sultana. Variation in the shape of these structures 

 can be seen in various directions in the statoblasts found in the. 

 same portion of a colony of F. austi'aliensis, but rather towards 

 an ovate appearance. 



Diagnosis. — Young form closely adherent and branched; older 

 colonies detached in younger parts; polypides seen only at the 

 ends of filaments. Tubes not cylindrical, brown; tentacles 28-30, 

 arranged in an elliptical corona; lophophore horseshoe-shaped in 

 retracted condition. Not keeled, and devoid of dissepiments. 



Statoblasts few in number, brown or black; broad elliptical, 

 slightly ovate, or very slightly flattened on one side parallel to 

 longer axis of the ellipse. 



The chitin composing the ectocyst is about 0-003 mm. in thick- 

 ness, and is quite clear when examined in section. It is always 

 covered externally by a material of equal or greater thicknes.s, 

 consisting of a brownish matrix, abundantly scattered through 

 which are the frustules of diatoms, etc. The stems of the colony 

 appear in section as roughly triangular, in a great number of 

 instances having the form of an equilateral triangle. At first, I 

 was inclined to regard this as being due to lateral pressure in 

 the process of sectioning the chitin, but the regularity of the 

 occurrence and of the form itself, and contrast with the chitinous 

 portion containing the polypide seems to disprove this. In this 

 way we probably have another point of diflference between this 

 species and F. sultana, in which the tubes are C3dindrical, the 

 older ones keeled on one side. No traces of dissepiments (usually 

 found, in an incomplete state, in F. sultana) can be seen in this 

 species, near the commencement of branches or elsewhere. 



The lophophore is not circular, like that of F. sultana, but 

 elliptical. The tentacles, 28-30 in number, are towards the base 

 united by a tentacular membrane, and cross-sections in this region 

 measure 0*38 mm. in length, and 0-23 mm. in breadth. The 



