6 GEAF ZU SOLMS-LAUBACH— MO^^OGEAPH OF THE ACETABULAEIE.*:. 



so that the chamher is eventually bilobed (Plate I. fig. 4). The upper of the two lobes is- 

 the corona superior, from which the young hairs at once begin to grov\^ ; the lower gives 

 origin to the corona inferior, at the upper margin of which the sporangial ray springs 

 from the basal portion. And since all these processes of development go on in exactly 

 the same fashion in the neighbouring chambers they remain in close connection and form 

 themselv^es into the marginal region of the disc. 



Harvey has given beautiful representations of the habit of the delicate Acetahularia 

 (§ Polyphysa) Peniculus. The long calcified stalk, provided with a foot at the base and 

 beariiig a cap at the apex, is furnished at intervals with small nodular swellings, each of 

 which bears a crown of circular scars, the points of insertion of a whorl of hairs. Cramer 

 found these still in situ on certain specimens, and I also have seen them. But the disc 

 consists of a variable, relatively small number of rays, which are quite free from each 

 other and attached at the base to a small lateral projection of the central portion. Eacli 

 such ray corresponds to a chamber of the margin of the disc of Acetahularia mediter- 

 ranean and adjoins, as in that case, a vestibule which forms a fold-like bend of the central 

 portion — i. e. the projection described. On the ray the same parts are to be distin- 

 guished, but the differentiation of basal portion and sporangial ray is here much sharper. 

 The latter has the form of an ovate-clavate, bladder-like swollen sac, with a rounded 

 margin, and is connected with the almost cylindrical basal portion by its much narrowed 

 base closed by a transverse wall. On the upper surface it bears a process somewhat 

 broadened at its blunt apex and completely free all round, its particular part of the 

 corona superior which shows on its apical surface 2 or 3 large broad scars of hair-tufts. 

 These Cramer [5] at first overlooked, but subsequently [6] described on the whole accurately. 

 "When three scars are present they form a triangle with the base turned outwards, and 

 when there are only two they stand obliquely behind each other, not straight as Cramer 

 has said. A true corona inferior is wholly wanting, unless one follows Cramer in 

 regarding as one the slight arching-out of the basal portion beneath. The calcification 

 of the membranes is to some extent perceptible in the stalk only and is not present in 

 the rays of the cap, or if so only as a very slight surface incrustation covering it all 

 equally. The spores are of regular globular form, and otherwise on the whole similar 

 in their structure to those of Acetahularia meditcrranea (conf. Plate II. tigs. & 7). 



Of the genus Polyphysa, thus distinguished by its wholly free rays of the cap and its 

 globular spores, for a long time only two species were known, both from Australia, viz. :— 

 P. asperfjillosa, Lamour., and P. Cliftoni, Harv. An examination of Harvey's original 

 specimen of the latter, which I was enabled to make by the kindness of Prof. Perceval 

 Wright, resulted in the view that at the most this form may be regarded as a variety of 

 the other with somewhat longer, more blunt, more clavate, and less swollen sporangial 

 rays, but in all other points in exact agreement. Besides, in examining numerous 

 specimens of Acetahularia Peniculus, caps are sometimes found which show an approach 

 to the Harveian form. The sporangial rays of the original are entirely without lime, and 

 filled with collapsed spores (from this cause polygonal in form), to which the thin sunken 

 sporangial membrane has become so closely pressed that it appears crumpled. The 

 same thing is to be seen in herbarium specimens of the normal form which have been 

 very slightly calcified. 



