BY E. ETHERIDGE, JUN. 83 



'These normal corallites, in the present specimen, average one 

 niillimetre in length, in the direction of the chain. 



The alteration that the tissues have undergone is even of a 

 more rigorous nature than that described by me in Hah/sites 

 australis. The walls are thickened, in places inordinately so, 

 the original tissues where visible being composed of grey or 

 brown sclerenchjma, but for long distances, several milli- 

 metres in fact, the entire WcjII is replaced by blebs of 

 chalcedonic quartz that have quite destroyed the original 

 matter. At times, although much less frequently, the inter- 

 corallite walls are similarly effaced, but the tabulae never. 

 In one particular corallite this thickening has progressed so 

 far as to practically reduce the visceral channel to a mere 

 narrow tube, and another has been similarly reduced by 

 chalcedonic blebs. 



In a horizontal section prepared for the microscope, where 

 least alteration has taken place, the corallites are seen to be 

 oval in outline, the inter-corallite walls a|)parently stout and 

 solid, and without any definite proof of the presence of 

 interstitial corallites in them, a very important feature in the 

 structure of Halysites. Here and there are traces of the cut 

 edges of tabulae, and scattered around the edges of the 

 visceral chambers small round bodies are not infrc-quently 

 seen, of the same colour and texture as the sclerenchyma of 

 the walls. Th'^se have a very suspicious resemblance to the 

 distal extremities of septa protruding through the infilling 

 calcite from a lower level, as is so frequently seen in corals 

 of a Favositoid nature. In more than one instance, I believe 

 I can detect a process protruding more or less horizontally 

 from the wall just as a spiniform septum should. There is 

 some reason to believe, therefore, that we are here dealing 

 with a septate form, and consequently, in the additional 

 absence ot interstitial corallites, with one allied rather to 

 Halysites escharoides than H. catenulatiis, for in these two 

 points lie the great distinction between the species in question. 



In a vertical section, similarly prepared, I have also quite 

 failed to detect any interstitial corallites. The tabulae are 

 well developed and complete, concave, and from three to four 

 in the space of one millimetre. 



The conclusions I am led to by an examination of this 

 coral, and making all allowance for its state of preservation, 

 are — (1) That it is distinct from Halysites australis^ mihi 

 (2) that it appertains to the group of H. escharoides, rather 

 than to that of H. catenulatus ; (3) whether it is identical 

 with the European H. escharoides is a more difficult question 

 to answer, but I am inclined to think not. 



This last opinion is based on the much greater size of the 

 reticulations formed bv the laminae, and a laxer form of 



