Algal Genera Acicularia and Acetabulum 331 



vestibules, though these afterward become obscure. It may be 

 remarked, too, whether significant or not, that the vestibule com- 

 municates with the base of the ray by an elongated slit (Fig. 35) 

 lying transverse to the main axis of the plant and that the passage- 

 way at the base of the primary sterile branch just previous to its 

 final closure is a similar slit also transverse to the main axis of the 



- 



plant (see scars in Figs. 5 and 6). 



II. Acetabulum crenulatum (Lamx.) Kuntze 



Acetabulum crenulatum, like Acetabulum Androsace, as de- 

 scribed by Strasburger,* and Acicularia Schenckii, as described 

 above, has more or less enlarged rhizoids densely filled with a 

 finely granular material which presumably serves as a reserve 

 food supply. The mode of development of the disc and its parts 

 is essentially as is described above for Acicularia Schenckii. As 

 in that plant, one very rarely finds incipient rays which bear 

 rudiments of three polytomous filaments instead of two and these 

 are always equidistant in a terminal whorl. One such case is 

 represented in our Fig. 17. It would be of interest if those who 

 have access to the growing Acetabulum Androsace with its more 

 numerous coronal "hairs" or hair-rudiments would determine 

 whether or not these 4—7 outgrowths orginate in a perfect verticil. 

 We are familiar only with the figures of Solms-Laubach bearing 

 upon this point. His figure 4 (/. c, pi. 1) indicates the possibility 

 of such an arrangement, but his Fig. 7, in which the sporangium is 

 still in a very young stage shows the rudiments of the sterile 

 branches in a straight radial row. From analogy with Acicularia 

 Schenckii and Acetabulum crenulatum and from the relations of 

 these parts as described by Solms for the matured Acetabulum 

 polyphysoides and Acetabulum Mobii,\ it is to be expected that the 

 coronal " hairs " of each ray in Acetabulum Androsace also will be 

 found to exhibit a terminal verticillate arrangement at the time of 



their 



origin. 



III. Acetabulum Caraibicum (Kutz.) Kuntze 



Acetabulum Caraibicum, % in our opinion, cannot be satisfacto- 

 rily distinguished from A. crenulatum. Through the courtesy of 



*Bot. Zeit. 35 : 715-718. 1877. 



t Acetabularia Mdbii Solms, Trans. Linn. Soc. Bot. II. 5 1 : 30. pi. 4./. /. 1895. 



t Acetabular ia Caraibica Kutzing, Tab. Phyc. 6: 33- P L 93- ,8 5 6 - 



