GEPP—MARINE ALG AND MARINE PHANEROGAMS. 389 
of Madame Weber van Bosse. By the kindness of M. Hariot and of Madame Weber 
we have seen and examined these two portions of the type, and we find that both in 
habit and structure it possesses the generic characters of Avrainvillea and not of Udotea. 
The filaments are uncalcified, branch dichotomously, bear no side branchlets, and are 
not parallel but are more or less intricated to form a feltwork as in all species of 
Avrainvillea. In almost all the species of Udotea the whole plant is generally more 
or less calcified, the main filaments run out almost parallel from the stipes to the 
periphery of the frond, bearing in many species lateral branchlets of peculiar form. 
We have therefore transferred U. amadelpha, Mont., to the genus Avrainvillea. 
In the original specimen many short thickish stalks spring from a thickened crowded 
base and generally branch dichotomously, each bearing a small rather thin frond, the 
whole plant being of a brownish colour and about 6 em. high. The basal part has a 
more or less felt-like hairy appearance, caused by the projection beyond the surface of 
the ends of filaments composing the stem. 
A. amadelpha has never been recorded since the original description was published, 
and we were therefore greatly interested to find specimens of it in the collections of 
Mr. Stanley Gardiner, who gathered it from reefs and deep water in five different 
localities more or less in the neighbourhood of Galega. Some of these plants are less 
congested in their habit of growth and attain larger dimensions, up to 17 or 18 cm. 
(the stalks themselves being about 6 cm., the height of the entire plant described by 
Montagne). These large plants all come from deep water, 25-47 fms., whereas the 
congested forms, which exactly resemble the type, were collected on reefs exposed at 
dead low water. 
A. amadelpha is distinguished from other species of the genus by the peculiar form 
of the apices of the frond-filaments, which are torulose (fig. 19), sometimes irregularly 
swollen on one side, often twisted and curved and often so interwoven as to form a 
thin pseudo-cortex of the frond (fig. 20). The filaments do not, as a rule, diminish so 
markedly in width towards their apices as is the case in 4. lacerata, to which species 
A. amadelpha is in structure closely allied. 
29. Avrainvillea Gardineri, sp.n. (Plate 49, figs. 28, 24.) 
Planta elata usque ad 30 em. alta, solitaria; rhizomate crasso luride fusco, 9-12 em. 
longo, 1°5 cm. crasso, e basi bulbosa suboblique adscendente, et in stipitem brevem 
compressum (1°5-2°5 em. longum, 6-9 mm. Jatum) viridem apice subito mutato ; 
fronde e olivaceo viridescente (nunquam brunneo) amplissima (usque ad 18 ecm. 
alta et 20 em. lata) rotundata, basi plerumque cordata vel auriculato-cordata, 
membranacea, zonata, margine primo integra, demum senectute plus minusve 
grosse lacerata; frondis filamentis laxe intertextis et facile separabilibus, 20-30 K 
crassis, apices versus haud attenuatis, plerumque regulariter torulosis, ad apices 
interdum leviter tortuosis sed inter sese vix intertextis. 
Cargados Carajos, 22, 30, and 47 fms. 
This species is a deep-water form and one of the largest members of the genus so far 
as we know it, rivalling 4. nigricans, Decne., the biggest species of the West Indies, and 
SECOND SERIES.—ZOOLOGY, VOW. XII. fie By 53 
