SOLITARY CORALS. 191 



beyond the lip of the calice ; the costae are somewhat slender and form sharp ridges 

 projecting unequally at different levels, but never prominently. On the other hand, 

 it resembles P. caryophyllus, from the Eocene of Sheppey, in having only four cycles 

 of septa. (It seems very probable that these two Eocene species are identical, the 

 presence or absence of a fifth cycle of septa not being sufficient to distinguish them.) 



I have no hesitation in referring a and b to P. stokesi, but I am more uncertain 

 about c. If it cannot be referred to this species, it cannot be anything else than 

 P. procumbens; but a comparison of M. Edwards and Haime's figm-es (35, plate x., 

 figs. 6 and 7) lead me to believe that the latter species is only a variety of P. stokesi, 

 and that the three Ceylonese specimens are local varieties of that species. 



Paracyathus striatus, Philippi. 



Cyathina striata, Philippi, ' Arch, fur Natur.,' 1842, vol. 1, p. 48. 



Paracyathus striatus, M. Edwards and Haime, 'Pol. foss. des terr. palseoz.,' 1851, p. 25. 



A single specimen, from deep water off Galle, which only came into my hands after 

 this paper was written, must clearly be referred to this species. 



Rhodocyathus, n. gen. 



Corallum simple, free, saucer-shaped, with signs of former adherence. Calice sub- 

 circular, wide, shallow. Columella essential, well developed, composed of numerous 

 oblique thin overlapping lamellae whose upper edges are produced into numerous 

 flattened spines. Septa in six systems and five cycles, the last cycle incomplete. 

 The primary and secondary septa subequal, very exsert, arched at their outer ends 

 and sloping inwards to join the columella ; their upper margins furnished with blunt 

 spines ; their outer margins produced into sharp and prominent spines where they 

 pass into the costse ; the surfaces of the septa marked with broad radiating ridges 

 corresponding to the marginal spines, the whole surface finely granular. Tertiary 

 septa similar to the primaries and secondaries, but smaller and less exsert. The 

 quaternary much smaller than the tertiary septa, and bending inwards to join the 

 latter near the columella. The quinary septa mostly very small and free at their 

 inner ends ; where they are longer they generally become attached to an adjacent 

 septum, usually to a quaternary, but in some cases to a primary, secondary, or 

 tertiary; the inner ends of the quinary and quaternary septa are very thin and 

 cribriform. The costse corresponding to the first four cycles of septa form distinct 

 fairly prominent ridges covered with fine granulations ; those corresponding to the 

 fifth cycle very small ; the costae of opposite ends meet below and cover in the basal 

 scar of attachment. 



Rhodocyathus ceylonensis, n. sp. Plate I., figs. 1 and 1a. 

 The characters are those of the genus. A single specimen from Trincomalee. 

 The dry corallum is of a yellowish colour, and measures about 18 millims. in height 



