GRAF ZU SOLMS-LAUBACH — MONOGRAPH OF THE ACETABULARTE.E. 7 



There arc described in this paper several species which, from their characters, approach 

 Acetahularia FenlculiiSi although sufficiently distinct from it. Tliey Avant, however, so far 

 as I could observe, the transverse wall between the basal portion and the sporangial rays, 

 and they diflPer farther in the form of the latter, which, for example, in my Acetahularia 

 exigua (Plate II. figs. 1 & 1) are somewhat cucumber-shaped and concave above, and 

 in the number and arrangement of the hairs on the parts of the corona superior. 

 Moreover, many of themje. g. A. parvula, n. sp. (Plate II. fig. 5), A. pohjpliDSoldes, Crouan, 

 show a ditference in the mode of calcification of the rays of the cap, which in these instances 

 is not equal all round, but much more abundant on the side-walls adjoining each other, 

 and is often present there only, so that the spaces between the rays are filled with lime 

 and bind them together with the appearance of a closed disc. There would be very 

 little, therefore, against the supposition, after this discovery in a mature state, of an actual 

 development in the manner of Acetahularia mediterranean in which the final dissolution 

 of the rays held together only by the lime incrustation takes place by the swelling and 

 destruction of the common middle layer of the partition-walls. If we learn from the 

 latter species how little weight is to be attached to these characters for a generic 

 separation of Acetahularia and Polyphysa, this appears clearer than ever if w^e pass 

 such a series of species in review as I have placed in the section Acetabuloides, and 

 contrast them with our one European species forming the section Acetabulum. The best 

 kno^Ti forms of this series are the nearly related A. crenulata and A. caraihica, Kiitz., 

 round which a number of other species are grouped. In Acetabuloides the corona 

 superior and corona inferior are developed in the same way as in Acetabulum, but their 

 parts are not continuous with others laterally, are, on the other hand, smaller than the 

 basal portions of the rays, and present knobs or processes completely free all round, 

 although often closely adjoining. It is remarkable that this character has been 

 overlooked by all authors who have dealt with the genus. 



Woronin says [31, p. 201], "Dans le 4*"™nome (185G) des ' Tabuhc pliyc' Kiitzing 

 decrit et represente une nouvelle cspece de V Acetahularia: A. caraihica ; mais cette espece, 

 a ce qu'il me semble, ne diff'ere en rien de V Acetahularia mediterranea " ; and Cramer, 

 who is otherwise so accurate, says [5, p. 21] : " The caps of A. crenulata are provided 

 above and below with collars, and the upper appears to differ in no respect from 

 A. mediterranea.'^ All have observed that the connection of the sporangial rays in 

 Acetabuloides does not reach to the outermost point, and that in consequence the margin 

 of the disc appears toothed or notched. Agardh was the first to found on this point a 

 division of the genus into two sections, which agree exactly with mine, although more 

 precise knowledge of the distinctive characters was then wanting. 



In regard to the firm lateral connection of the sporangial rays, the forms belonging to 

 Acetabuloides show differences. In none of these species is this union so firm as in 

 A. mediterranea ; indeed, two species are described — viz. A. Caly cuius, Quoy et 

 Gairaard (Plate III. figs. 6, 7, 10, 13), and J. Farlowii, n. sp. (Plate III. fig. 1), — which in 

 the complete separation of their rays come very near to Polyphysa, from which they are to 

 be distinguished only by the presence of a well-develoj)ed corona inferior. In most of 

 the species, certainly, the rays remain, after decalcification, more or less united laterally 



