THE ALGAE OF BERMUDA. 75 



Dr. M. A. Howe. It is certainly not C. Zosterae Farlow, 1881, p. 86, 

 Alg. Am.-Bor. Exsicc., No. 162, but resembles C. virescens Farlow, 

 1881, p. 85, Eudesme virescens P. B.-A., No. 33, which is the same as 

 Mesogloia virescens Carmichael in Wyatt, Alg. Danm., No. 49. 

 Though some writers speak of C. virescens as having a solid axis, C. 

 Zosterae as hollow, for instance Bornet, 1892, p. 236, the statement is 

 true of the former only in the earlier stages. " A section of the frond 

 of a well-developed C. virescens shows a circle of roundish cells around 

 a central cavity"; Farlow, 1. c. The description and figure of C. 

 Zosterae Borgesen, agree with the Bermuda plant. 



In New England and northern Europe there are two species of 

 Castagnea, which are well distinguished by Farlow as C. virescens and 

 C. Zosterae; the former resembles the Bermuda plant; the latter, 

 quite distinct, is the Myriocladia Zosterae Crouan, Alg. Mar. Finistere, 

 No. 49, and the Castagnea Zosterae of Le Jolis, 1863, p. 85, fide spec, 

 authent. ; but it may be open to question whether it is the Mesogloia 

 virescens var. zostericola Harvey, 1846-1851, PL LXXXII, of which 

 Harvey says " only differs in being of smaller size, with less compound 

 ramification; there is no microscopic character to distinguish it." 

 And in the Nereis Bor.-Am., part 1, 1852, p. 127, where he recognizes 

 two species as distinct, he questions the identity of his Mesogloia 

 Zosterae with the species of Lyngbye and Areschoug. His plate X. B, 

 M. virescens, is drawn from a specimen from Sand Key, Florida, to 

 which we will refer later; we do not think it is the M. virescens of 

 New England and northern Europe. Plate X. A, M. Zosterae, is 

 incorrect and misleading, as pointed out by Farlow. If it should 

 prove that Rivularia Zosterae Mohr, 1810, p. 367, was identical with 

 Mesogloia virescens Carmichael, Castagnea Zosterae would be the proper 

 name for the spring plant of New England and northern Europe, and 

 a new name would be needed for the smaller summer plant now known 

 by that name. As to the identity of C. virescens of New England and 

 northern Europe with the Bermuda plant, we are not now prepared to 

 point out distinctive characters. But the southern plant is usually 

 stouter, less branched, and with a firmer gelatine. For the purpose 

 of comparison we have examined a large number of specimens of 

 Castagnea (or Mesogloia) virescens of northern Europe and New Eng- 

 land, including specimens from Mrs. Griffiths, Mrs. Wyatt, Greville, 

 Harvey, Le Jolis etc. ; with very few exceptions they bore unilocular 

 sporangia; none had plurilocular. Of Castagnea (or Myriocladia) 

 Zosterae we have examined a considerable number, including speci- 

 mens from Le Jolis and Crouan, and the No. 162 of Farlow, Anderson 



