80 RECORDS OF THE AUSTRALIAN MUSEUM. 



tabulate, the tabulae far apart (they are nearly half a mm. apart), 

 although complete, the intertabular spaces vertically elongate, 

 and both the walls and tabulfe greatly thickened, (PI. xvii., 

 fig. 7) as compared with the similar parts of the normal corallites. 

 There is not the slightest trace whatever of the small projections 

 in the interstitial tubes, " apparently of a septal nature," dis- 

 covered and described by N^icholson.* 



The presence of the interstitial corallites, and the absence of 

 septa clearly places the present coral within the group of H. 

 cateaiulatus, the " Chain-coral " of the Wenlock, but as compared 

 with the latter there is this remarkable difference. In //. catenu- 

 latus the tabuhe of the normal corallites are " comparatively 

 remotely disposed," whilst in the interstitial tubes they are " much 

 more numerous and more closely set."f In our coral, which I 

 propose to call Halysites ausiralis, the exact opposite is the 

 case. 



It is customary with Monographists to include in H. catenulatus 

 a large number of other forms, in former days regarded as separate 

 species, purely from external characters, but I think before this 

 indiscriminate lumping is done, the whole of such forms should be 

 submitted to microscopic examination, when possibly ditferences 

 of an equally important nature to that shown above, may be found 

 to exist. 



Halysites ausiralis difi'ers from //. agglomerata, Hall,| by the 

 same characters that it does from //. catenulatus, Linn. In the 

 form of the reticulations and mode of growth it is more akin to 

 H. lahyrinthica, Goldf.,§ and H. catenulatus, var Harti, Eth.,|| 

 but in both cases the fenestrules are larger than in our species. 



The specimens were collected by the Rev. J. Milne Ourran, at 

 Molong, N. S. Wales, and by him presented to the Trustees. 



* Loc. cit., p. 229, t. 11, f. 1. 



t Ibid., p. 228. 



Z Hall— Pal. N. York, ii., 1852, t. 35 bis. 



§ Petrefacta Germanic, t. 25, f. 5a. 



II Quart. Journ. Geol. Soc, xxxiv., 1878, p. 583, t. 28, f. 2. 



