249 



The large mass of coral discover-ed oi? Glenelg is appar- 

 ently identical with — ■ 



Plesiastpw^a uevillei, Edwards and Hairae (C), p. 490. 



The authors' definition of the species has been trans- 

 lated by Tenison-Woods as follows: — ''Corallum somewhat 

 flat with sublobed edges; epitheca on the edges rudimentary > 

 calices very slightly salient, close but distinct, circular or 

 sometimes a little deformed ; columella rudimentary ; three 

 cycles, but a fourth in two systems where the primary equal 

 the secondary, thus giving the appearance of eight systems 

 of three ; septa rather broad, hardly exsert, thin, finely and 

 regulately dentate, striate, and granular; pali broad, little 

 exsert, rather thin, the primaries the strongest. In section 

 the exothecal dissepiments are almost hoi'izontal, 1 mm. 

 apart ; columella of a very lax tissue, scanty and formed of 

 lamellar processes : endothecal dissepiments extremely thin, 

 sometimes wavy, not always parallel, sloping inwardly, | 

 mm. apart ; wall compact, rather thick, seldom or only 

 slightly united to others. Diameter of calices 4 to 5 mm. 

 In shallow places, King George Sound." (D), p. 323. 



The "Challenger" dredged "a small flattened specimen" 

 of this species ofi' Fiji. 



The two species — P. urvillei and P. peroni — bear a close 

 resemblance to each other. They may be distinguished by 

 the calices of the former being slightly larger than those of 

 P. peroni, also of about ec|ual size, and are equally salient ; 

 whilst the calices of P. peroni are relatively smaller, more 

 unequal in size, and unequally salient. Examples of P. 

 peroni, in small, fiat, or nodular masses, can occasionally 

 be picked up on the shores of the Gulf and Kangaroo Island. 

 The largest example found by the writer was a hemispheri- 

 cally-shaped specimen, 3^ in. in diameter by If in. high, 

 from the north coast of Kangaroo Island. Prior to the late 

 important discovery I had obtained two beach specimens 

 which I referred to P . nrvillei. ' One of these was a cylin- 

 drical fragment, 5^ in. long and 2 in. in diameter, picked 

 up on the north coast of Kangaroo Island ; and the second, a 

 fragment dredged at the time of excavating the Outer Har- 

 bour, which measured 5-J- in. long, 5 J in. broad, and 2^ in. 

 thick. Both fragments had been broken off from larger 

 masses and showed no peripheral outline of the corallum 

 from which they had been respectively detached, so that no 

 estimate of the size of the parent mass could be made, but 

 the fragments were regarded as of abnormal size. From the 

 occurrence of beach specimens at widely-separated locali- 



