ON THE GENERA ANADYOMENE AND MICRODICTYON. 67 
anciennement décrite par Velley et dont le Muséum posséde un frag- 
ment rapportó des Iles Sandwich par M. Gaudichaud, à laquelle on 
pourrait appliquer le nom spécifique de Velleyanum, pour rappeler celui 
du botaniste qui le premier l'a bien fait connaitre ; l'autre, signalé - 
comme variété du C. umbilicata, par M. Agardh, conserverait le nom 
e M. tennius. Ces changements me paraissent d'autant plus mo- 
tivés que le caractère tiré de la fronde ombiliquée peut s "appliquer 
indistinctement à chacune des espéces, aujourd'hui connues, et qui sont : 
1. Hydrodictyon umbilicatum, var. tenuius, Ag. Syst. Alg. 85; 2. Con- 
Serva umbilicata, Velley, Linn. Trans. v. 169. t. 7; 3. Anadyomene 
Calodictyon, Mont. Pl. Cell. Canar. 180.” In the Ann. des Sciences 
Naturelles, série 2. xvii. 327, M. Decaisne quotes— 1. M. Agardhianum ; 
2. M. Velleianum; 8. M. tenuius. 
Endlicher, in his * Mantissa Botanica, sistens Generum Plantarum 
Supplementum Tertium,’ 1843, places the genus Microdictyon with 
the genera Hydrodictyon and Talarodictyon, in the family Hydrodictyez, 
but the fructification of AMierodietyon is unknown, and there is no rea- 
son to believe that the cells produce perfect netted plants as in the 
freshwater genus. 
Endlicher also refers to the genus Dictylema of Rafinesque, Somio- 
logia, n. 54, as a synonym of the genus. 
Miss Endlicher refers to three species of the genu 
. M. Agardhianum, Dec. 64.— Hydrodictyon solicit, var. 
Tur Agardh, Syst. 85. Mare Rubrum. 
. M. Felleyanum, Decaisne, 1. c.— Conferva. umbilicata, Velley in 
Lim. Trans. v. 169. t. 7, ad insulas Sandwichenses. 
. M. Montagneanum.—Anadyomene Calodictyon, Montagne, Flora 
Pes Plant. Cell. 180. Mare Atlanticum. 
It is to be observed here, that though the names of two are quoted 
as Decaisne's, he has changed two of them. 
M. Decaisne, in his paper above quoted, believes there are three 
species, but he does not attempt to give any characters to distinguish 
them, except the localities where they are found ; and Professor Harvey, 
though he found three species, gives a name only to one of them, 
which he regards as similar to those described by Montagne from the - 
Canaries. Kützing, in his Species, in p. 512, gives specific characters 
for M. Agardhianum and M. ems eit eopied from Montagne, 
who gives it to distinguish from his 4 : oe Tam 
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