43 



the encls of component filaments. Montagne published no figure and though his description is 

 quite a good one, and has been copied by De Toni in Syll. Alg. I. p. 509, the plant has 

 never been recognised since. 



In the following year, 1858, was published Zanardini's account of algae collected in 

 the Red Sea (1. c). This paper had been read before the Lstituto di Scienzia at Venice in 

 1857, but as the actual publication apparently did not take place till 1858, it is obvious that 

 Montagne takes precedence of Zanardini. Zanardint describes among his Red Sea algae a 

 new genus Chloroplegma for the reception of a species which he calls C. sordidum. We have 

 not been able to examine his specimens, but from the description and figures and locality we 

 have no hesitation in identifying it with Montagne's Udotca amadclpha. The likeness in habit 

 between his fig. 1 a and the type of U. amadclpha is obvious, while the plant represented in 

 fig. 1 . with its larger and more regular fronds, probably represents a form from deeper water, 

 such as we have found (fig. 114) in Mr. J. Stanley Gardiner's collection from the islands of 

 the western Indian Ocean and described in Trans. Linn. Soc. (Bot.) VII. 1908, p. 178. 



Till recent times it has been unusual to find records of the depth from which any 

 marine alaa has been collected and of the conditions under which it was erowino- • and this 

 omission has no doubt prevented the recognition of what are mere growth-forms, or at least, 

 has led to a misconception of the limits of certain species. Now that deep water forms are 

 more generally obtained by dredging, the importance of taking into consideration the vertical 

 distribution is obvious. Mr. Gardiner's specimens of A. amadelpJia gathered on the reefs, in 

 the western Indian Ocean, exposed at dead low tide are about 5 or 6 cm. high and shew 

 the congested habit of Le Duc's plant from Galega, as well as that of Zanardini's figure 

 quoted above. The deep water plants on the other hand dredged from depths ranging from 

 25 to 27 fathoms, attain a height of 1 7 or 18 cm., the stalks alone being as long as the entire 

 reef-grown plant. The fronds are large, not torn, and show the zonate marking clearly. The 

 structural characters are identical in both forms (figs. 113, 115). A deep water example has been 

 figured in our account of Mr. Gardiner's Algae (1. c). The specimens collected by Col. Pike 

 at Mauritius, preserved in the British Museum Herbarium, are clearly reef-forms, beino- small 

 and congested, though not at all eroded. Possibly they grew in quiet water. 



A. amadelpJia is distinguished from other allied species by the peculiar twisted, torulose, 

 curved and often unilaterally and interruptedly swollen apices of the frond-filaments (figs. 113, 

 1 15), which are often so intenvoven as to form a thin pseudo-cortex of the froncl. This character 

 is very marked in Montagne's type and also in some of Mr. Gardiner's specimens, but in 

 others of his collection and in Col. Pike's Mauritius plants this pseudo-cortex is not so well 

 developed. However the ends of the frond-filaments are sufficiently curled and twisted in all the 

 specimens to shew their identity. We have not so far been able to connect the development 

 of this pseudo-cortex with any special conditions of the plant, such as depth of habitat. 



A. amadclpha belongs to the "Formenkreis" of A. lacerata. In structure it is most closely 

 allied to the West Indian A. asarifolia, but differs from it in habit. For in A. amadclpha the 

 stipes is always branched and bears a few or many fronds according to whether the plant is 

 much or little submersed; and the fronds are subrhomboid-rotundate with cuneate to rounded 



