REPORT ON CORALS — HYDROCORALLISLE. 59 



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conical tip (PI. II. fig. 3, S). Just above the level of the top of the style is a circlet of 

 small rough projections, which stand out from the wall of the gastropore and contract its 

 bore at this point. 



Around the mouth of the gastropore is a circlet of from about ten to fourteen 

 dactylopores, arranged symmetrically at equal distances from one another and from the 

 centre of the mouth of the gastropore. The mouths of these pores are elongated towards 

 the axis of the gastropore, so as to open into, and become continuous with, the cavity of 

 this latter pore (PL II. D Z, D Z). The openings of the dactylopores are continued down 

 as wide slits, for some distance on the upper part of the wall of the gastropore, so that 

 the pores have, as it were, two mouths placed at right angles to one another 

 and confluent with one another, the one opening to the exterior, the other into the 

 cavity of the gastropore. The cavity of each dactylopore consists of a wide upper 

 chamber in the region of the widely open mouth (PI. II. TZ, TZ), and a narrow tubular 

 continuation of this, which traverses the ccenosteuni in a direction parallel with that of 

 the axis of the gastropore for about half the length of the latter. Against the outer 

 wall of the pore is a small ridge-like excrescence, with an hirsute surface, which is 

 the style of the dactylozooid (PI. II. fig. 3, S'), and which is described by Pourtales as 

 " a rudimentary septum in the shape of a hairy fringe " (Pourtales, I.e., p. 34). 



The dactylopores in each cyclo-system are separated from one another by thin plates 

 of calcareous matter which are directed inwards radially towards the axis of the gastropore 

 (PI. II. fig. 3, P), and which at first sight have all the appearance of the septa of 

 Hexactinian corals, and have hitherto been mistaken for such by observers. They are 

 however, composed each of two thin laminae of dense calcareous matter, united by some- 

 what less compact calcareous substance, which is freely perforated by canals for the 

 passage of offsets of the coenosarcal meshwork. The thin laminae are merely the 

 juxtaposed walls of the adjacent dactylopores. These radially disposed plates, which 

 may be termed pseudosepta, have their inner edges continued down the wall of the gas- 

 tropore for a short distance beyond the margins of the mouths of the dactylopores as 

 well-marked vertical ridges, which soon become merged in the general surface in their 

 course (PL II. fig. 3). 



The cylindrical masses formed by each cyclo-system are sometimes flat, often gently 

 rounded at the top. Their summits are irregularly circular in outline, but have an 

 indented border, the indentations corresponding with the centres of the pseudosepta 

 in position, and representing the intervals between the opposed dactylopore walls, which 

 are here not obliterated by growth of ccenenchym. 



The cyclo-systems, when viewed from above in a line looking directly into the 

 mouths of the pores, show, in all essential particulars, the same structure as that which 

 occurs in Allopora profunda, which is represented diagrammatically in PL II. fig. 13. 

 The styles of the tentacular zooids, S S, appear as small projections in the interspaces 



