7. Anthozoa (incl. Hydrocorallia). B. Alcyonaria. 33 



Metaldetes n. 1, Protopharetra 2 n. ; Syringocnemidse Syringocnetna n. 1. 

 From a general consideration of the skeleton the author suggests that the soft 

 parts occupied the intervallum and covered the two walls, but the central 

 cavity, except in 2 or 3 aberrant genera, was probably empty, as in the sponges. 

 While presenting some resemblances to corals, the Arch, are more closely allied 

 to the calcareous sponges; practically all the form variations described can 

 be paralleled by the sponges and by them alone. Perhaps the calcareous 

 sponges and calcareous Crelenterates have been derived from a common an- 

 cestor and the Arch, present evidence of the modifications of the generalised 

 type* which gave rise to the Calcarea and Anthozoa. 



B. Alcyonaria. 



See Grieg, W. Me Intosh, Nutting (V), Simpson ( 2 , 3 ), Broch( 3 ). For fossil Helio- 



pora see Fe!ix( 1 ). 



Miiller( 1 ) traces the growth of the oocyte of Tubipora chamissonis. The 

 young oocyte ingests a neighbouring Nahrzelle the nucleus of which de- 

 generates. The egg-nucleus is spherical or oval, with a thin membrane, and 

 has a sparse achromatic network. The > Binnenkorper also has a membranous 

 outer envelope and contains a network on which are fine granules of nucleolar 

 substance and chromatin; on the periphery of the Binnenkorper are chromatin 

 nucleoli, which stain intensely. The oocyte, when about 4 /< in diameter, be- 

 comes enveloped by a follicle of small indifferent cells, which arise from the 

 endoderm of the short filaments; the oocytes and their follicles project from the 

 mesentery in bunches. The follicle epithelium, which is a single layer, 

 secretes at its base a cuticular double membrane, one layer of which is applied 

 to the follicle and the other, which is thicker and laminated, to the oocyte. 

 The follicle cells secrete the yolk which is found scattered through the proto- 

 plasm, except peripherally, in the form of spherical or irregular masses; the 

 oocyte grows to 40-50 (i in diameter. The maturation changes were followed 

 in Clavularia, Paralcyonium and others. The membrane of the Binnenkorper 

 disappears and its chromosomes enlarge considerably, the chromatin breaks up 

 into granules which wander into the egg protoplasm, the nuclear boundary at 

 the same time vanishing. The author interprets the nonstainability of the 

 nucleus about this stage as due to the complete change of the chromatin into 

 nucleolar substance. There are no analogues of polar bodies and no maturation 

 or reduction division. The chromatin reduction associated with the matu- 

 ration is brought about by transformation of idiochromatin into trophochromatin, 

 which, as chromidia, wanders out into the egg protoplasm; the reduced nucleus 

 changes completely into nucleolar substance from which the female pronucleus 

 arises. The author records the presence of large larvae in the ccelenteron 

 of Sclerophytum polydactylum. 



K. Kinoshita( 4 ) obtained numerous planulse of Anthoplexaura dimorpha, some 

 being artificially removed from the parent colonies, obtained near Misaki at 

 the end of July and early in August. These orange coloured planulse, 1.2 mm. 

 long and .3 mm. broad, were free swimming for a fortnight. Within one or 

 two days after fixation the formation of tentacles and stomodaeum took place. 

 The polyps grew only slowly, but when large enough, they were fed with eggs and 

 larvse of Echinoids, and then they grew rapidly. At the end of October the vessels 

 containing the polyps were tilted over and sunk one fathom deep in the bay; there 

 the polyps grew so rapidly that in a week they were as broad as the parent polyp 

 and in a fortnight produced buds. Spicules appeared during the metamorphosis, 



