162 PKOF. W. N. BENSON AND DE. S. SMITH ON [vol. lxxix, 



Morphology. 



Habit of growth and external form. — Little need be 

 .added to the statements made in defining the genus. The corals 

 were all weathered and otherwise imperfect ; 8 to 10 cm. may have 

 been the original length of the largest of them, and the greatest 

 diameter measured was about 4 cm. It is not improbable that 

 larger examples may be found. None of the specimens exhibited 

 .a calice. 



Internal structure [ephebic stage]. — Septa. In sections 

 4 cm. in diameter there are approximately 60 septa in each of the 

 two cycles. The septa may remain united to the epitheca, or 

 become separated from this enclosing wall and in some cases leave 

 quite a wide area between it and their outer ends (PI. VIII, fig. 1: 

 upper part of figure). The major septa penetrate the columella, 

 but the minor, which are about two-thirds as long as the major, do 

 •not reach the axis. The septa are thus numerous and crowded, 

 and display a pseudo-radial symmetry; the cardinal fossula (al- 

 though not conspicuous) can be distinctly recognized (in PL VIII, 

 figs. 1 & 3, and PI. IX, fig. 2). Alar septa cannot be located in 

 section ; but their position is discernible on the sides of the 

 ^corallum. 



Columella. — The large columella is the most distinctive 

 feature of the genus. It is elliptical and cuspidate in section ; the 

 approximate ratio of the longer axis to the shorter ranges from 

 1 : 05 to 1 : 075 (the former being about 9 mm. in length, and 

 the latter 5 to 6'5 mm.). The cusp projects into the cardinal 

 fossula. It has a fibrous structure presenting a feather-like 

 appearance in longitudinal section (PI. VIII, fig. 2), and a radial 

 and concentric one in transverse section (PI. IX, fig. 2). It is 

 built up of slightly curved conical layers superimposed one upon 

 the other. Within this columella are seen in transverse section a 

 short medial plate and the inner ends of the major septa. The 

 medial plate is very distinct in most sections examined ; but it 

 varies in length in the different specimens : in no case, however, 

 does it completely bisect the structure (see PI. VIII, fig. 1 & 

 PI. IX, fig. 2). In the latter figure it is seen to be in continuity 

 with the cardinal septum. It may be noted also, though less 

 distinctly, in PI. VIII, fig. 3. 



The major septa reach the medial plate, although the}>- are not 

 easily traced through the columella. They are there obscured by 

 the fibrous texture of the columella itself, and are difficult to follow 

 ■ on account of their twisted nature ; it is possible, nevertheless, to 

 distinguish them when the section is carefully examined with 

 a lens. PI. VIII, fig. 1 illustrates the columellar structure above 

 described f airly clearly. 



A few minor septa may also, it is possible, be represented by the 

 lamelhe within the columella, as in Carruther sella and Ciononden- 

 dron (p. 164), although, as is also the case in these genera, the 

 .minor septa do not themselves reach the solid axis. 



