to 



REPORT ON CORALS— HYDROCORALLIN^S. 61 



order to display the connections of the deeper reticulation with the dactylozooid and its 

 general arrangement. The connections of the reticulations with one another are well 

 seen at the cut edges of the bisected zooid systems, as shown in the plate. 



A tortuous and complicated mass of large canals springs from the bases of the 

 gastrozooids at their margins, but not from their under surfaces. Some of these large 

 canals turn also immediately after springing from the gastrozooids upwards, through 

 the wall of the zooid system, to join the main network already described as communi- 

 cating with the dactylozooids. The remainder of the large canals form a tortuous 

 reticulation which passes down through the ccenenchym of the ccenosteum, by the side of 

 the immediately adjoining zooid system, to anastomose with the corresponding reticula- 

 tion arising from the base of the gastrozooid of this latter. The walls of the ampullae, 

 as shown in the figure, are traversed by a fine reticulation of the ccenosarcal canals 

 beneath their covering derived from the superficial layer of ectoderm. 



Nematophores, composed of nematocysts of the usual larger form, are placed on the 

 pseudosepta, between the dactylozooids (PI. VII. N N). 



Zooids. — One form of dactylozooid and one of gastrozooid only are present. 



Dactylozooids. — These, in the retracted condition, are short cylindrical bodies, with 

 a rounded, blunt-conical, free extremity. They widen out towards their attached 

 extremities, and are united to the sides of the dactylopores which are outermost in the 

 systems, and to their styles, by elongate bases, which are drawn out below into narrow 

 prolongations which join the ccenosarcal meshwork. The zooids are, in fact, attached in 

 an- almost precisely similar manner to that in which the dactylozooids of Spii^ora 

 echinata are fixed within their groove-like pores. The free cylindrical portions of the 

 dactylozooids in the present species are bent upwards, so as to extend in the wide upper 

 cavity of the dactylopore in a direction parallel to that of the axis of the gastropore. 

 They are seen thus projecting in the centrally placed zooid system represented on Plate 

 VII. D Z, showing partly free above the inner margin of the dactylopore sac, partly seen 

 through the transparent sac of the gastrozooid. A curved line, crossing them trans- 

 versely, marks the point where the sac of the gastrozooid becomes bent over and unites 

 with that of the dactylozooid. The dactylozooid surfaces, as well as those of the tentacles 

 of the gastrozooids, are thickly set with nematocysts of the usual smaller form. 



Gastrozooids. — These are short and broad cylindrical bodies somewhat contracted in 

 diameter towards the middle of their length. They terminate above in a dome-like 

 kypostome with the mouth opening at its apex, and are provided with a single whorl 

 of light tentacles set on immediately below the hypostome. The tentacles are, in the 

 contracted condition, very short and stout, with swollen, rounded, knob-like extremities, 

 which reach to a height only just exceeding that of the summit of the hypostome. At 

 the margins of their bases the gastrozooids (PI. VII. G G) are drawn out into a series of 

 large radially-disposed canals which lead directly into the cavities of the zooids, and 



