OF NEW SOUTH WALES. 323 



CyphastrjEA muelleri, Ed. Sr H. 



Less hispid than the preceding ; columella rudimentary, septa 

 unequal and exsert, probably only a variety. 



Both the above species are probably found on the S. E. coast, 

 near Port Jackson, though I have no well-authenticated habitat. 



Genus Plesiastr^a. Ed. fy H., 1846. 



Corallum a convex mass, rising from a costulate plateau ; calices 

 shallow, circular, edges free ; columella spongy ; costse and 

 exotheca well developed ; septa exsert, stout, continuous, and 

 denticulate ; pali well developed before all the septa except the 

 last, budding always in the intercalicular spaces. The genus dis- 

 tinguished from all the Astreacaja with free calicular margins by 

 the presence of pali. 



Plesiastr^a urvillei. Ed. fy H. Syn. Astrea galaxea. 

 Quoy 8f Gaimard. Voy. de V Astrolabe, Zooph. p. 216, pi. 17, 

 /. 10-14 



Corallum somewhat flat with sub-lobed edges ; epitheca on the 

 edges rudimentary ; calices very slightly salient, close but 

 distinct, circular or sometimes a little deformed ; columella rudi- 

 mentary ; 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 regularly dentate, striate, and granular ; pali broad, little 

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

 exothecal dissepiments are almost horizontal, 1 mil. apart ; 

 columella of a very lax tissue, scanty and formed of lamellar 

 processes ; endothecal dissepiments extremely thin, sometimes 

 wavy, not always parallel, sloping inwardly, J mil. apart ; wall 

 compact, rather thick, seldom or only slightly united to others. 

 Diam. of cal. 4 to 5 mil. In shallow places King George's Sound. 

 Messrs. Q. and Gr. say that the animal is confluent and of a 

 beautiful grass green. 



