7. Anthozoa (incl. Hydrocorallia). A. Zoantharia. 25 



the smaller ones gradually develop their testes. When the length is 15-17 mm. 

 all the mesenteries have testes but only those on the larger ones are as yet 

 functional. The spermatozoa escape by temporary ducts. The corallum shows 

 5 lines of growth which probably correspond to annual periods, and there are 

 usually at this time 20 septa fusing by trabeculse in the axial fossa. In 

 specimens of about 20 mm. in length ova commence to appear and gradually 

 replace the testes as the latter shed their products. Finally 2 or 3 large 

 ova occupy the whole area of the former testes. There seems to be at this 

 time a renewal of the activity of the calicoblastic layer. With increase 

 in size over 25 mm. the ova ripen and escape by ducts formed through the 

 thickened nutritive endoderm and their place is taken by newly-formed ova. 

 In the largest specimen 40 mm. long and in others a little smaller many of 

 the ova had escaped and no small ova were being formed to take their place 

 and the whole endoderm was devoid of fat and much vacuolated. The polyp 

 probably now dies. A similar condition was found in Comopsammia willeyi\ 

 in Madrepora pulcra, var. alveolata in which most of the ova had been shed 

 the polyps were dying. Probably the death of the individuals and colonies 

 above described is due to some innate reason. The maximum of productiveness 

 has been reached, the parent gradually becomes less fruitful and ultimately 

 dies. It seems that the ripening of the sexual organs of a large number of 

 polyp colonies of the same species in a single locality or habitat, followed by 

 the death of all these colonies, is a regular phenomenon. See Gardiner( 2 ). 



Gardiner( 4 ) describes the structure of the corallum and polyp of Fldbellum. 

 F. is said to be distinguishable from Blastotrochus by the presence in the latter 

 of buds between the calicular margin and the base, but the author has found 

 a similar condition in F. rubrum; the presence of attached young appears to 

 be an accidental circumstance. Again the hollow rootlets supposed to be 

 characteristic of Rhizotrodms are also present in some specimens of rubrum. 

 This species is protandrously hermaphrodite. The author decribes small canals 

 extending from the base of two ova through the endoderm; one ovum seems 

 to have partially flowed into its canal. These canals are merely temporary 

 structures for the escape of the ova. Young specimens of rubrum with 6 large 

 and 6 small septa and 6 pairs of large and 6 pairs of small mesenteries appear 

 at first sight as if the tissues of the polyp have been torn off the mouth of 

 the calicle but there is no trace of rupture or tearing and the polyps are well 

 preserved. All the mesenteries are attached above to the body wall which 

 formes a rim round the mouth of the calicle about Ys the breadth of the latter. 

 There is no trace of tentacles or of stomodseum at this stage but in a stage 

 with 48 septa the latter is present as an extremely shallow invagination. 

 There is no true columella in F. In pavoninum all the septa of the polyps 

 are entocrelic and have tentacles over them, where as in rubrum half the septa 

 are exocoelic with no correspondingly situated tentacles. The mesenteries of 

 the former are hence twice as numerous as the septa and those of the latter 

 the same in number. 



WhitfJ6ld( 1 ) describes a dome-shaped specimen of Mceandrina labyrinthica in 

 the centre of the upper surface of which a species of Ctenophyllia is enclosed. 

 The two are so intimately blended that 3 of the ridges of the M. pass directly 

 into the adjoining ones of the C. When collected both were alive and in 

 perfect condition. Vaughan ! ) emphatically denies that two genera are 

 represented but holds that the specimen merely shows the variations which 

 may take place within a single colony. Diploria geographica n. founded by 

 Whitfield in another paper is merely a form of the very abundant labyrinthi- 



