OF NEW SOUTH WALES. 303 



Two specimens of this very interesting coral are in the Mac- 

 lea j an Maseum. It differs very much in the form of its pali and 

 in general shape from all our other species, and is more like 

 Deltocyathus viola. But the pali do not unite to one another, 

 though they are united to the septa, being little more than lobes. 



Trochocyathace.e. — Pali in many circles round the columella. 

 Genus Trochocyathus, M. Ed. and H., 1848. 



Corallum simple, pedunculate or subpedicellate, or with only 

 faint traces of adherence ; columella well developed, composed 

 of bundles or series of prismatic or twisted processes ; pali well 

 developed, entire, free to a great extent, unequal according to 

 the cycles to which they belong, and present before all the cycles 

 except the last ; septa exsert, broad, and laterally striate ; wall 

 bare, or with only a rudimentary epitheca. 



All the known species are fossils extending from the Lias to 

 the Pleistocene, but most numerous in the Miocene. There are 

 two fossil species in New Zealand, figured, but not described in 

 the Quart. Jour. Geol. Soc, Vol. 6, 1850, p. 331, pi. 28, fig. 18 and 

 19. Milne Edwards doubts if they can be arranged under the 

 genus (see Nat. Hist. des. Cor., Vol. 2, p. 46). They are both 

 from Pleistocene beds in Onekakara, New Zealand, and are named 

 Trochocyathus hexagonalis, and T. Mantelli, Ed. 8f H. ut supra. 



2. — Trochocyathus Meridionalis. Duncan. 



The corallum is short and hemispherical in shape, marked 

 externally by subequal costas, and a depression at the base, small, 

 and circular in outline. The costa3 are separated by distinct 

 intercostal spaces, are very prominent at the calicular margin, and 

 faintly marked with wavy swellings, and their external surface 

 near the base has a row of rounded granules. The primary and 

 secondary are slightly larger than the tertiary, and the higher 

 orders are smaller than the latter. The calice is circular in 

 outline, and shallow. The septa are distinct, unequal, distant and 

 smaller than the costas. They are broad extrnally, and exsert, 

 but they soon become narrow, granular laterally, and depressed 

 below the circular margin. There are four cycles in six systems : — • 



