Zoology.] NATURAL HISTORY OF VICTORIA. \Fdyzoa. 



Plate 68, Fig. 2. 

 IDMONEA AUSTRALIA (P. McGil.). 



Description. — Polyzoary dichotomously branched, branches spreading irregu- 

 larly, contorted, and twisted on themselves ; 4-6 cells in a series, the inner the 

 longest, surface punctate ; back of branches longitudinally sulcate, the intervening 1 

 ridges punctate. 



Port Phillip Heads, 10-15 fathoms. 



The only specimen I have with a distinct point of attachment is 

 \ inch high by f across. Numerous others, evidently broken off 

 close to their origin, are about the same size. The polyzoary is of 

 a dirty-white color, dichotomously irregularly branched ; the 

 branches angular in front, slender, frequently spreading in various 

 directions and slightly twisted on themselves, occasionally a third 

 of a revolution or even more. There are about 4-6 cells in a 

 series, the inner the longest, the outer little projecting. The 

 surface is finely punctured and obscurely granular. The back of 

 the branches is rounded, deeply sulcate longitudinally, the ridges 

 between the sulci punctate. 



This species may prove to be a form of /. Atlantica, but at 

 present I think it better to describe it as a distinct species. 



Explanation of Figures. 



Plate 86.— Fig. 2, specimen, natural size. Fig. 2a, front of a branch, magnified. Fig. 25, 

 back, magnified. 



Plate 68, Fig. 3. 

 IDMONEA RADIANS (Lamk.). 



Description. — Polyzoary rising from a narrow base ; branches narrow in front, 

 dichotomous, spreading in a radiating manner ; cells 1-4 in a series, the inner very 

 much projecting, smooth, mouth bilabiate ; back of branches ridged longitudinally, 

 with the intervening sulci pierced by a single row of round or oval pores ; ovicells 

 anterior, situated immediately below a bifurcation, and embracing the cells on both 

 sides for about 5 series, divided by elevated ridges, and with the intermediate surface 

 pitted. 



Reference. — Busk, Brit. Mus. Cat., pt. iii., p. 11., pi. vii., fig. 1-4. 



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