78 



cimens occur where the apices of the rays are truncate or have 

 only an undulated margin. 



The segments of Corona superior (Fig. 63 B) have a somewhat 

 irregular form, oblong cordate, often somewhat emarginated on 

 the side turned outward and bear 2 — 3 hair-scars. In some spe- 

 cimens we generally fmd two scars, seldom three, in others three 

 and only seldom two. They may be found one behind the other 

 or quite irregularly. The shape of the Corona superior therefore 

 agrees well with the figure of Solms and the same may be said 

 of that of the Corona inferior (Fig. 63 C) ; the segments are here 

 almost rectangular, but somewhat laced in the middle. The 

 breadth of the disc is about 3 — 5 mm. 



The gametangia (Fig. 64) are spheri- 

 cal and occur in a number of about 80 

 in each ray. They are about 160/^ broad. 

 A very large number of gametes are 

 developed in them. Contrary to what 

 is the case in Acetahularia mediterranea 

 where the gametangia get free and only 

 after a resting period, often lasting several 

 months, develop the gametes, these here 

 come to existence while the gametangia 

 Fig. 64. Acetahularia Caliculus are still enclosed in the rays. The game- 



Quoi et Gaimard. tangia are opened bv means of a similar 



Summit of a sporanguun ^ . ^ 



with two large holes one in cover as m ^. mediterranea. At the same 



each corner and containing i^yne as the gametangia are opened, large 

 emptied gametangia. ^ .* ^ \ T 



(About 35:1). holes are formed m each corner ot the 



rays, through which holes the gametes can 

 escape (Fig. 64). It seems that these holes arise simultaneously in 

 all the gametangia of the disc, at all events it has. been the case in 

 all the discs I have seen in this stage of development. The gametes 

 are ovate ; the cilia I have not been able to see with certainty, 

 though the gametes occurred here and there in the emptied game- 

 tangia or in the rays ; I have seen them lying in couples or more 

 or less joined together, also some larger roundish bodies were 

 found, most likely zygotes, and longer cylindrical cells : young 

 plants. 



Yet I may add that the plant does not seem to have any 

 fixed growing or resting period ; at any rate plants collected in 

 the months of January and February were found in all difYerent 

 stages of development. 1 have found quite young plants without 

 disc but with two or three whorls of iuiirs in accordance with 



