274 ME. J. E. DUEEDEN ON 



the column ; the latter has narrowed and become cylindrical, but 

 still shows only eight alternating dark and light areas. The 

 eight tentacles are finger-shaped, rounded at their free extremity, 

 and able to move about, but, as in the adult, are incapable of 

 retraction. The oral disc is flattened, its ectoderm still retains 

 the zooxanthellse, and the mouth is circular or oval-sbaped. 



The dorsal tentacle is a little stouter and longer than the 

 others, and the originally smaller ventro-lateral tentacles are now 

 practically o£ the same size as the three remaining members o£ 

 tte first series, i. e., the ventral tentacle and the two median 

 laterals. The dorso-laterals, however, have lagged considerably 

 behind in their development. At their base they are also pushed 

 out slightly further from the disc than the other six, which now 

 are beginning to form a cycle by' themselves. 



The larvae are clearly sensitive to the action of light. When 

 settling they would select the under surface or a crevice in any 

 fragment of coral-rock placed in the vessel, and if the fragment 

 were turned over would detach themselves and move to some 

 less exposed spot. The adults usually live associated in shady 

 crevices, the pseudo-tentacles and . tentacles protruding as a 

 delicate fringe. During the ordeal of examination under the 

 strong tropical light, the larvse would slowly assume a more or 

 less collapsed aspect, their healthy inflated appearance returning 

 after being shaded for some time. This behaviour towards light 

 I find also to be very general amongst adult Actiniaria and 

 Madreporaria. 



Several examj)les were kept alive for six or seven days, but 

 none passed beyond the stage represented in fig. 7. No trace 

 was presented of the pseudo-tentacles. The development of 

 the larvse after extrusion was at first very rapid, the stage last 

 mentioned being reached within forty- eight hours. The only 

 external alteration during the next four or five days was a slight 

 increase in dimension of all the parts, without any indication of 

 additional tentacles or mesenteries. Unfortunately, circumstances 

 did not permit of further observation. 



The chief external characters, other than that of size, in which 

 the adults differ from the oldest larvse are : (1) the presence 

 of several cycles of entacmseous tentacles, arranged in the 

 formula 6, 6, 12, 24, 48, the members of any cycle being equal j. 

 and (2) the six (normally) large branching " pseudo-tentacles,' 



