120 Mr. J. E. Gray's Outline of an Arrangement of Stony Corals, 



exhibited in L. selaginoides, where it must be possible to find 

 a great many stages at one time on a single spike, as so many 

 oophoridia occur on it. They must be also very easy to prepare 

 for examination here, — a matter of exceeding difficulty in L. den- 

 ticulatum. 



In conclusion to these remarks on the oophoridium, two words 

 on the affinities of Isoetes and Lycopodium. It appears to me 

 that this question involves the import which must be attributed 

 to the large spore-sporangia of Isoetes. Are these metamor- 

 phosed branches or not ? In the latter case the affinity would 

 be merely apparent, only inasmuch that both, Isoetes and Lyco- 

 podium J exhibit two kinds of spores. In the former case, how- 

 ever, the affinity would be perfectly proved. The compressed, 

 concentrated stem of the Isoetecs would not be any great evidence 

 against the affinity, since we have become, through Kunze, ac- 

 quainted with the genus Phylloglossum. This is apparently a con- 

 necting link between Isoetes and Lycopodium ; and if A. Braun^s 

 opinion be correct, that Phylloglossum is to be regarded as a Ly- 

 copodium acaule, Isoetes would also have to be regarded as a 

 planta acaulis of the Lycopodiacece. It is readily conceivable 

 that the term stemless plant is not to be taken here in its strictest 

 sense, but rather to be understood as indicating a plant with an 

 abbreviated stem. 



Lastly, in reference to the import of the germinative spore of 

 the oophoridium, BischofF (Krypt. Gew. 126) has called them 

 spore-bulbels [tubercula sporoidea), and compared them to the 

 bulbels of Arum ternatum and Dentaria hulbifera. It is evident 

 that this has no meaning till we know the whole cpurse of de- 

 velopment. The same applies to the expression receptaculum 

 tuber culiferumy which he applied to the oophoridium. I have 

 preferred the latter name because it is the more simple. 



[To be continued.] 



XV. — An Outline of an Arrangement of Stony Corals. 

 By J. E. Gray, F.R.S. &c. 



About ten years ago, when I arranged the Corals in the British 

 Museum, I was struck with the difficulty of determining with 

 precision the proper situation in the system either of Lamarck 

 or De Blainville, of a large number of the specimens we then 

 possessed, and in the ' Synopsis ' I made some remarks on the 

 variation which accidental circumstances, such as localities, &c., 

 appeared to have on specimens of the same species. Since that 

 period I have examined the collections of corals which have 

 come in my way, and selected for the Museum collection the 



