A. J. Shearfibij — On Opercidate Corals. 551' 



Derrengullen Creek, however, exliibits the remains of eight stout 

 rootlets (PI. XXVI, Fig. 19). There were probably more than 

 this number on tlie complete coral, as the apex is missing, and 

 specimens collected at this locality which have the apex show 

 remains of at least six on this part of the coral. 



Of these rootlets some ai'e scattered over the ventral surface, but 

 most of them are situated along the lateral angles. They are hollow 

 and cylindrical, and in some cases branching, atid range from mere 

 filaments to as much as a millimetre in thickness. The specimen 

 figured presents another example of calicinal gemmation, the young 

 coral in this case completely filling the caliceof the parent form, and 

 exhibiting also an instance of abnormal growth, one side of the coral 

 having grown much faster than the other. 



The I'emaining figures illustrate some fine examples of rootlets on 

 It. inter punctatnm and U. australe from the same locality. In my 

 previous paper I stated that 1 had only found a couple of specimens 

 showing the exothecal processes, and these consisted of small 

 protubei'ances at the apex, the remains of probably very small and 

 delicate processes. I figure one (Fig. 16) showing two little knobs 

 about the middle of the ventral surface, which I said might be the 

 remains of rootlets. I am now able to say that my surmise was 

 correct, as I have several examples of this species, which, besides 

 having a liberal allowance of I'ootlets along the lateral angles, possess 

 extra ones at or near the middle of the ventral surface. Figs. 20-22 

 are specimens of R. inter pimctatum which exhibit very clearly the 

 tubular anchoring stolons projecting from the lateral angles. Fig. 21 

 shows three strong lateral rootlets and the remains of one near the 

 middle of the ventral surface. Fig. 20 is an interesting specimen 

 showing a small parent coral from which has budded a much larger 

 form. This younger coral shows three strong rootlets and one more 

 delicate growing from the lateral angle. 



Figs. 23 and 24 are specimens of E. australe which exhibit both 

 lateral and median rootlets, Fig. 23 also possessing one on the dorsal 

 surface. 



Nearly all my previous specimens of RhizopJiyllum were obtained 

 in the shale beds at Hatton's Corner, Yass, and in spite of the large 

 number collected there, only two showed faint traces of rootlets. On 

 the other hand, every specimen, with few exceptions, obtained 

 recently during an afternoon's search at this new locality showed 

 remains of well-preserved rootlets in many instances. 



It would seem, then, that at Hatton's Corner they had been 

 subjected to violence of some kind before being finally deposited in 

 the shale bed. The violence probably consisted of being rolled to 

 and fro by the action of the waves in the vicinity of the coral reefs 

 which abounded there at that period. The worn and rounded pieces 

 of other corals occurring at Hatton's Corner, in places giving the 

 shales an amygdaloidal appearance, should, I think, help to confirm 

 this opinion. 



The occurrence of the delicate rootlets on RhizophyUum in an 

 almost perfect state at Derrengullen Creek, together with soqie 



