240 RECORDS OF TUE AUSTRALIAN MCSEU.M. 



We may now ascertain liow far the Murrumbidgee form 

 agrees with tliis definition. In the first place, however, all 

 macroscopic characters must be omitted as the various coenos- 

 teum fragments are matted together in black limestone, and not 

 weathered-out. The longest measurable fragment is 35nim., 

 and tlie general diameter of the branches 2inra. 



In viewing a transverse section tlie agreement with the 

 structure of A. ramosa as portrayed in Prof. Nicholson's figures- 

 is ]-eniarkable. The axial tube is always visible, and of com- 

 paratively large size. This is surrounded by the sectioned 

 zooidal tubes of variable size and outline, piercing the homo- 

 genous compact (in fact dense) skeletal tissue. Xicholson 

 described two conditions of the surface, as already explained, 

 both of which may be seen in our sections. In some instances 

 the peripheral ends of the zo(')idal tubes are visible as clear 

 cellular spaces, like those of an ordinary ramose coral, more or 

 less quadrangular iu outline; these then represent that con- 

 dition of Aiiiphipora in wliich the surface apertures of the 

 tubes are not covered by a thin membrane. In other sectioned 

 branches the peripheral area or ring is occupied by vesicles 

 over the greater portion of its extent, in conjunction with other 

 vesicular tissue in the before-mentioned zooidal tubes ; such 

 may possibly represent the second condition of Amphi'pora iu 

 which the apertures are covered with a membrane. The 

 tissues are all compact and opaque, there is no trace of 

 porosity, and I have failed to distinguisli tabulae. 



In longitudinal sections I found it very difficult to exactly 

 locate the axial tu.be. This arose no doubt from the various 

 angles at which the branches are disposed in the matrix. All 

 the characters described under the transverse section are 

 repeated here. 



A comparison with Prof. Nicholson's figures (two of wliich 

 are reproduced for comparison) with those now given, will at 

 once indicate the close agi-eement there is between the two 

 foi'ms — European and Australian. Whether other forms have 

 been des(;ribed since he wrote, I am unaware, but if his state- 

 ment still holds good that A. ramosa is the only known species 

 so far, the present fossil will be a welcome addition and may be 



- Nicholson— Loc. cit., pi. ix., fig. 3, pi. xxix., figs. 5 and 6. 



