410 PROF. P. M. DUNCAN ON THE [June 19, 



and may be liexneonal, pentagonal, quadrangular, and triangular, or 

 even deformed. The margins of the calices are sharp ; the septa are 

 non-exsert, unequal, some being very long and others quite rudi- 

 mentary, and the cyclical arrangement is confused in the extreme. 

 There is little or no difference between the primaries and secondaries, 

 and some part of a system usually aborts. Three cycles of septa in 

 six systems with some higher orders, abortion taking place here and 

 there, is the rule ; and the more irregular the outline of the calice, the 

 greater is the confusion of the septal arrangement. The columella 

 is small, lax, and trabeculate, being formed by processes from the 

 septal ends. 



The costaa are distinct and unequal low down on the corallites, 

 and indistinct and absent higher up, although in some instances 

 they can be traced to the calicular margin. The larger costae 

 have nodules on their free edge placed in linear series, and often 

 extending over an intercostal space and smaller costce to the next 

 large one. Tliese nodnles join those of approximated costae of 

 neighbouring corallites, and form short processes. Junction-processes 

 occasionally do not correspond to costa;. An epitheca exists over 

 each corallite, especially low down ; it covers tb.e cosite and inter- 

 costal spaces and laps round the junction- processes ; it is membra- 

 nous-looking and has a few transverse and other ridges. A small 

 amount of exotheca exists between the coslfe, and the endotheca 

 is largely developed, coming up to the base of the calices, and 

 usually closing them below, but the dissepiments are not, very 

 close. The growth is by gemmation, which may occur anywhere 

 on the outside of a corallite from below the calicular margin to close 

 to the base. 



Height of the corallum or colony 4 centim., breadth 10 centinl. 

 Width of calices from 3 millim. to 1 centim. 



Loralify. West coast of India, shallow water, fixed on an 

 Oshea. 



The new form is distinguished from its nearest ally Phymaslraa 

 profundior, Ed. & H., by having well-developed costae, non-exsert 

 septa, and extremely irregulai' calices. 



VI. Revrarks on the Structures o/"Phymastr8ea profundior. 



The attachment of the colony or corallum is by a comparatively 

 small base to a shell, and it does not appear that it sprang from one 

 corallite. The bases of several corallites may be seen in contact with 

 the shell ; and it is evident that they and their buds contribute to the 

 symmetrical development of the whole colonj^ The corallite walls 

 are solid and thick, except where they are growing at the calicular 

 margin. The buds, when they arise close to the calicular margin of 

 the parent, produce a certain amount of thinning of the parent wall, 

 and often give the appearance of fissiparity. Lower down, the buds 

 communicate with the visceral cavity of the parent ; and there is a space 

 at their base, where they spring from the parent, which leads into its 

 interior. 



