277 — 



On the uppermost part of the stalk there is a basin-shaped 

 disc in consequence of the upwards curved rays; it has about 

 26 — 28 rays which are united in the living plant but immediately 

 separate after decalcification with acid. According to So lms the 

 plant ought to have: "Rays even in the living state separate and 

 free". This however was not the case with my specimens and this 

 is the most essential difference between my specimens and the 

 description of Solnis. Yet I do not think this is so very impor- 

 tant. One of the 

 above-named spe- 

 cimens from Fre- 

 mantle in the British 

 Museum and con- 

 served in spirit, re- 

 ally had a few se- 

 parate rays but most 

 of them were con- 

 nected and when 

 seen under micro- 

 scope a calcified 

 mass was also vi- 

 sible on the few 

 separate rays with 

 which they most 

 probably have all 

 been pasted toge- 

 ther. In the original figure also by Quoi and Gaimard they 

 are connected and Harvey writes I.e. tab. 249: "The coherence 

 between the cells also appears to be less strong than in other 

 species", but that they might be free he does not say. In this 

 connection I may also point out that Howe in Acetabularia 

 Farlowii, which according to Sol ins has separate rays, by exami- 

 nation of the plant in living state has found that "only about one 

 in four or one in five" of a thousand specimens has got it. 



The apices of the rays have broadly rounded corners and in 

 the middle often a large broad deepening (Fig. 6 A). This is espe- 

 cially developed in the older disc but is also often to be found 

 even in quite young. However it may be pointed out that spe- 

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

 only an undulated margin. 



Fig. 6. Acetabularia Caliculus Quoi et Gaimard. 



A. Part of the rays with gametangia. B. Corona 



superior with hair-scars. C. Corona inferior. 



Fig. A ahout 10: 1, B and C about 60: 1. 



