153 



rest. They are formed of a series of large, loosely-joined, 

 .flattened granules. The primaries and secondaries reach the 

 base, and the tertiaries nearly so. The intercostal spaces are 

 large and are crossed at regular intervals by very thin bars, 

 which form the fenestrated ornament characteristic of the 

 genus. 



Height, 5*5 mm. ; diameter of calice, 3'5 mm. 



Dredged by Messrs. Hedley and Petterd, 20 miles north- 

 east of Port Jackson, at a depth of 250 fathoms. Five ex- 

 amples were obtained, two of which are perfect, though their 

 mural perforations are clogged by sediment. The drawing 

 of the corallum is from a third specimen, one-half of which is 

 well preserved, and the other half imperfect ; the two remain- 

 ing examples are fragmentary. 



The calice of T. TIedleyi almost exactly reproduces that 

 of T. fenestrafiis, the common eocene coral, but in the shape 

 of the corallum the two species differ widely, the former be- 

 ing somewhat barrel-shaped, while the latter is long and has 

 a pointed base. T. Cho^kii, the miocene Tremafofrochus, is 

 also barrel-shaped, but its calice shows an additional cycle 

 of septa. The other species of the genus, both fossil and re- 

 cent, which have been described, differ more markedly from 

 the present one. 



Genus Trochocyathus, Milne-Edwards and Haime. 



Trochocyathus Petterdi, spec. nov. PL v., hgs. 2a, h. 



The corallum is small and curved. It is divided into two 

 approximately equal portions, the upper of which tapers very 

 gently dowuAvards to the commencement of the lower half, 

 when it suddenly contracts and then terminates in a narrow 

 bluntly-pointed base. The calice is circular, shallow, and 

 crowded with septa. At first sight it appears to be divided 

 into 15 eq^^al parts by as many principal septa, with three 

 others of higher order in each division. A close examina- 

 tion, however, shows that there are in reality six systems, of 

 which only one is perfect, ' i.e., with its full complement of 

 tertiaries; another has one tertiary only, while in the remain- 

 ing four these septa are entirely wanting. The quaternaries 

 and quinaries are regularly developed between the fifteen 

 principal septa. The total number of septa is thus 60. Those 

 of the fourth and fifth orders are equal in thickness, but much 

 smaller than the rest. All the septa are wav}^, and the qua- 

 ternaries especially so. Their margins are entire, and their 

 sides are studded with rows of strong, bluntly-pointed gran- 

 ules. Irregularly shaped pali are placed in front of 

 the secondaries and tertiaries, which are rather shorter than 

 the primaries. 



