-2 GEAF ZU SOLMS-LATJBACH— 310N0GEAPH Or THE ACETABULARIEJ?.. 



Museums, and the original specimens of Beccari's collection at Elorence. Single species 

 were sent to me by Professor Perceval Wright, Professor Agardh, Dr. Schenck, and 

 Professor Farlow, and I wish to express my indebtedness and thanks to all who have 



thus aided me. 



Of living AcetahulariecE there have been described three genera : \\z., Acetahularia, 

 Lam., Polyphysa, Lam., and Ealico^^yne, Harv., witli which Sender's genus Fleiophysa 

 is identical. To these are to be added the fossil forms established by Munier-Chalmas 

 and the genera placed here, Acicularia, d'Archiac, Briardina and Orioporella, Mun.- 

 Chalm. Of the two latter genera (not yet fully described) Briardina comes very near 

 to Acicularia, as I know from a kind private communication of its author ; Orioporella, 

 however, does not belong here at all, as he has recently convinced himself, and therefore 

 needs no farther mention. 



According to de Bary and Woronin's description the fertile pileate shoot oi Acetahu- 



laria mediterranea consists of the stalk, with its foot grasping the substratum ; of the 



basal portion, immersed in this ; and of the cap, which is partitioned by regular radial 



walls into chambers, which are in open communication with each other only in the 



middle, above the insertion of the stalk. This central flat area, covered with a level 



circular membrane terminating the apex above the insertion of the stalk, may be 



called the central area. It is surrounded by a continuous, circular, convex cushion, 



which I shall call the corona superior, belonging to the chambered marginal portion of 



the disc. The corona superior is farther composed of numerous firmly united radial 



sections or areas, the rays of the corona. Each of these radial areas bears a radial row 



of circular protuberances, or scars, which correspond to tufts of hairs that have fallen off 



or have remained incompletely developed and one-celled. The number of these scars 



varies. Cramer gives them as 4 to 5, though higher numbers may well occur. Where 



the hairs are complete they belong to the outer parts of the row in question. On the 



under side of the cap there are present, according to de Bary and Cramer, two concentric 



cushions surrounding the insertion of the stalk. The outer, more peripheral of these 



corresponds exactly with that found on the upper surface and may be called the corona 



inferior. It also is composed of exactly as many radial areas as there are chambers in 



the margin of the cap, but the hair papillae are wholly absent. The more central 



cushion, adjoining the stalk, is not sharply separate from the other, but gradually 



becomes merged in the central area. The peripheral one consists of what may be called 



the vestibules of the chambers of the cap, of which there is one for each chamber, but 



separated by a fold of the membrane like a transverse septum, which within shows only 



a small opening, frequently becoming obliterated by subsequent growth in thickness. 



While, therefore, each disc or sporangial ray stands in open communication with the 



relative sections of the corona superior and inferior, it is separated from its vestibule by 



the membrane described with a central perforation. The corona inferior and vestibules 



were first correctly described and figured by Cramer for A. crenulata. 



We have, then, in the middle the central area, into which open the narrow 

 vestibules, adjoining, but separated from each other by a thick meml)ranous process. 

 I^ext there is the peripheral crown of radial chambers, firmly united to each other 



