222 THE ANATOMY OF ACTINIA MESEMBRYANTHEM UM. 



In S. parasitica the disc will be found also marked with dots, as in 

 Fig. 15, pi. XII. These, however, were not, when I saw them, due to 

 the organ in question, but tc the bunches of eggs which show through 

 the disc, and that is so transparent that all seven pairs of septa in 

 each sextant are represented. 



The order of the septa can be well made out through the stomach 

 wall of T. crassicornis. The fluted organ is visible through the 

 transparent stomach wall but the white spots are small and faint. 

 When the stomach wall is much extended the quaternaries show 

 the line of white spots through the wall, but the other three septa 

 do not, as their arches being deep carry the line away from the wall. 

 The characteristic differences between the position of the eggs in 

 T. crassicornis on the one hand, and S. parasitica and A. dianthus on 

 the other, suggests an analogy to the vegetable kingdom, and to 

 those plants which carry their seeds or ovules on the fine edges or 

 sides of parietal placenta, as in the orchis and the poppy. 



In conclusion, I would venture to call in question the use of an 

 expression which creeps into several treatises. It is that of " imper- 

 fect septa " as applied to the tertiary and the quaternary forms as if 

 they were incomplete. So far as my observations go, they are 

 directly opposed to the idea suggested by those words, and I cannot 

 agree that either of the four pairs of septa which go by repetition to 

 make up the skeleton of the Actinia, are open to that appellation, 

 merely because they have not filled up the arches that distinguish 

 them respectively, or because they do not reach the stomach-wall. 

 I venture to think all are quite complete, and if they were other- 

 wise than they are then they would be imperfect, and would at once 

 necessitate some compensating change in the general arrangement 

 of this beautiful product of God's law of creation, whatever that law 

 may be. Obviously one result of the present arrangement is neat- 

 ness in packing, and considering the pressure sometimes exerted by 

 a contracting specimen this must be an important consideration. 



