THE ANATOMY OF ACTINIA MESEMBRYANTHEMUM. 219 



cut off from the animal. It is seen in its natural attitude in Fig. 5, 

 pi. XI, giving the septum a scolloped wavy appearance. A portion 

 of it is seen again magnified in Fig. 8, pi. XII, where the attitude 

 allows only one row of spots to be seen, and the angle is visible along 

 which it keeps its hold of the edge of the septum. On opening 

 A. mesembryanthemum, in the manner suggested above, the delicate 

 fluted edging will be found running along each septum in the attitude 

 pointed out, excepting on the primaries, and even on those occas- 

 ionally. Through the glass the delicate line of white spots may be 

 seen edging each secondary, tertiary, and quaternary septum, and if 

 each septum is turned over with a brush the corresponding line of 

 white spots on the other side will be visible. A needle will lift the 

 whole of the organ off the septum for inspection, but it leaves the 

 septum more freely the -second or third day after the animal has been 

 in the aquarium. It is more strongly developed at some seasons 

 than others. I have seen it best in autumn. 



If now we pass to T. crassicornis, we shall find that a different 

 relation of the parts under consideration exists, for the eggs grow 

 over the whole surface of the septum. Frey and Leuckart, and Teale 

 confine them in their drawings to a limited mesentery in front of the 

 septum, and filling up the arch where there is one, but I have seen 

 them as in Fig. 9, pi. XII, covering every portion of every septum, 

 even the primaries, and running right up to the craspedum itself, and 

 on to the band to which it is attached ; the ova green, pink, and white. 

 The craspedum again is not confined, as in A. mesembryanthemum, 

 to a special projection on the primary, secondary, and tertiary septa, 

 but edges them all, quaternaries as well, up to the very disc. On its 

 first appearance it is a single wavy line, as in Fig. 8, pi. XII, like a 

 shirt frill ; but subsequently, as the season advances, it bursts out in 

 a series of rich sprays up the edge of the septum, and always exhibits 

 a profuse gathering at the base of the septum, a normal characteristic 

 of all the Actinidce. It was a very long time indeed before I could 

 determine the attitude of the fluted organ in T. crassicornis ; it was 

 there, I knew, as I had frequently dissected pieces of it out. At 

 length I found it, and at the very back of the stomach -wall, as seen in 

 Fig. 8, where the stomach-wall or curtain is supposed to have been 

 removed. It would seem that in this species the craspedum runs 

 so far up the edge of the septum that it either pushes the fluted organ 

 before it, or does not leave it room to appear in the same position 

 as that in which it is exhibited in A. mesembryanthemu?n, so it passes 



