REPORT ON CORALS — HYDROCORALLIN^E. 69 



band in the spectrum when examined spectroscopically. The position of this band was, 

 however, unfortunately not determined. 



Dactylozooids. — The dactylozooids have bases of closely similar form to those of 

 the dactylozooids in Stylaster densicaulis and Allopora profunda, and are attached in 

 the same manner within their sacs, with the exception that they have no styles. The 

 free portions of the zooids differ, however, from those in the species just mentioned, in 

 that they are in the contracted condition, longer, more slender, and more gently tapered 

 towards the extremities. Moreover, instead of being retracted within their sacs in 

 a vertical position, i.e., one parallel to the length of the sac, they are in the present 

 form placed out of harm's way by being doubled down within the mouth of the sac 

 of the gastrozooid (PI. VIII. fig. 1, D Z, D Z). They were observed to be thus doubled 

 down between the pseudosepta and within the gastropore in the fresh corals when 

 dredged. 



Gastrozooid*. — The sac of each gastrozooid is narrowed at the horse-shoe shaped 

 opening, already described as leading, in the ccenosteum, from the upper chamber of the 

 gastropore to the lower chamber in which the gastrozooid lies. The sac is reflected over 

 the surface of the tongue-like process, and passing into the lower chamber, becomes 

 attached to the zooid near the margin of its base. The tongue-like process projects in 

 front of the mouth of the zooid, and must prevent the protrusion of the zooid, except 

 in a crooked direction. 



The gastrozooid itself is basin-shaped below, with a cylindrical mass above, the 

 bottom of which gradually expands to join the margin of the basin. The cylindrical 

 upper portion has a flat top perforated by the mouth, which is in the form of a crucial 

 slit, and is abutted on by regularly disposed elongate gastric cells of the endoderm. 

 Numerous large canals are given off from the periphery of the lower basin-shaped 

 portion of the zooid, but none from the under surface of the basin. The disposition 

 of these canals has already been described. The gastrozooids are devoid of tentacles. 



Gonophores. — Only one specimen of the present form was obtained, and it was of 

 the male sex. The male gonophores appear as large rounded lobulated masses resting 

 within the ampular sacs, and springing from stout offsets of the ccenosarcal mesh work, 

 which pass into the sacs to reach them. Usually two tiers of ampullar sacs encircle 

 each cyclo-system, being contained in the zone of ampullae described in the account 

 of the ccenosteum. 



The minute structure of the lobulated masses is shown in Plate X. As;. 10. A 

 membranous sac derived from the ectoderm, and containing abundant nuclei in its 

 tissue (S), lines the ampullar cavity and encloses the generative lobules. One or two 

 large offsets of the canals of the ccenosarcal mesh work penetrate this sac, and with the 

 ends of these the central mass of the generative structures is continuous. This 

 central mass is composed of spherical nucleated cells filled with granules, and closely 



