579 



away; whether the basal cell like that of A. mediterranea lives 

 longer and is able to develop a new plant I am unable to ascertain ; 

 but it seems most probable. 



This small Acetabularia seems to me to be very closely related 

 to Acet. Farlowii and Acet. Suhrii. Acetabularia Farlowii, of which 

 species I have had specimens for comparison from the Bermudas 

 collected by M.A.Howe, seems however to be distinguished com- 

 monly from A. Caliculus by having the apices of the rays in the 

 disc more or less broadly rounded, and in that the Corona superior 

 only has two hair-scars and also that the stalk has no or in any 

 case only feeble and few spindleshaped swellings on the upper- 

 most part and finally that the disc according to Howe is flattened. 

 But I may point out that the specimens in one of my gatherings 

 (Nr. 1617) from Long Point in some regards bare a close resem- 

 blance to Acetabularia Farlowii, especially by having the apices of 

 the rays most often broadly rounded and by seldom showing any 

 indication of emargination (Fig. 7). As the figure B shows, the Corona 

 superior almost had the same form as 

 in my other specimens of A. Caliculus 

 and had 2—3 hair-scars; the form of 

 the disc was basin-shaped. Yet this col- 

 lection showed a peculiarity, namely, 

 that two of the specimens had two 

 discs one over the other thus resem- 

 bling Acet. crenulata, but even quite 

 young plants had the rays rounded or 

 feebly undulated in the margin and not 

 at all apiculate as in A. crenulata, from 

 which the plants were very different. 

 That however specimens are found, of 

 which it may be difficult to decide the 

 species, is seen by M. Howe's remark 

 (1. c. 1905, p. 577): "The zones occupied 

 by the two species (A. Farlowii and 



A. crenulata) occasionally, however, overlapped; the individuals 

 intermingling in this common region were, as a rule, easily refer- 

 red at sight to the one species or other, though once in a while 

 an individual was met with whose affinities seemed at first a little 

 dubious". 



These specimens also greatly resemble Acetabularia caraibica 



Fig. 7. Acetabularia Caliculus 

 Quoi et Gaimard. Forma 



(compare text). Fig. A about 

 15:1, fig. B about 60:1. 



