150 Rhodora [AvavsT 
Under the supposition that all such balls were of similar origin and of 
algal nature, they were included in an algal genus Aegagropila, which 
comprised also some fresh-water confervoid Algae of a radiating- 
globular mode of growth. ‘The real nature of the Aegagropiles marines 
was apparently first pointed out in print by Weddell in 1879. He 
showed that they are not Algae at all, but principally the fringed-out 
and balled up fibrovascular bundles of Posidonia Caulini, a naiadaceous 
phanerogam (Actes du Congrès international de botanistes, d'horti- 
culteurs, de négociants et de fabricants de produits du règne végétal, 
tenu à Amsterdam, en 1879, 58-61; as abstracted in Just's Jahres- _ 
bericht, 9, 1879, 333). But Professor Farlow tells me that their ` 
real nature was understood before this, for in 1872 he collected speci- 
mens at Antibes, France (one of which is now in the Botanical Museum 
of Harvard University), and their formation from Posidonia was then 
known to the botanists of that place. A different explanation of the 
materials of which they are mainly composed was given in 1892 by W. 
Russell, who stated that they consist chiefly of the remains of pine cones 
(Revue générale de Botanique, 4, 1892, 545). ‘This conclusion was 
denied by Sauvageau, who again pointed out their composition from 
Posidonia bundles (Journal de Botanique, T, 1893, 34, 95). In the 
meantime, however, Russell had published a second article, repeating 
his statement about the pine cones, and giving a classification of the 
various materials composing such balls, both from fresh and from salt 
water, so far as known to him. He finds that, in addition to the pine- 
cone kind, some do consist of Posidonia with or without Algae and 
sponge remains, some of Zostera, some (in English lakes) of larch cones, 
some (in the lakes of the Engadine) of fir cones and fir needles, some 
(in the Lake of Geneva) of wood shavings. (Revue générale de 
Botanique, 5, 1893, 65, as abstracted in Beihefte zum botanischen 
Centralblatt, 8, 1893, 444). ‘This list, by the way, has much interest 
in connection with that given for American balls in my first article. 
Russell was in error as to the pine cones, and the Aegagropiles marines 
are now universally known to consist mainly of Posidonia, and they are 
thus described under that genus in Engler and Prantl’s Die natiirlichen 
Pflanzenfamilien, II, 1, 207. The distinction between the algal and 
the **kunstliche" Aegagrophila is also well brought out by С. de 
Lagerheim in Nova Notisaria 1892, Ser. III, 89. 
But other marine balls, of very different materials, have recently 
been reported from another direction. Under the title ** Water-Rolled 
