1902] Collins, — Marine Cladophoras of New England 115 



third type, hooked, curved or circinate, while the normal filaments 

 are straight and erect. In the species of Eucladophora the branches 

 vary in length and diameter, but not otherwise. In Kjellman's 

 paper before mentioned he uses the generic name Acrosiphonia with 

 practically the same extension as Spongomorpha, giving as his reason 

 that the characters given by J. G. Agardh a are essential characters 

 of the genus, while those given by Kiitzing,' 2 are non-essential and 

 uncertain. As, however, the earlier name Spongomorpha has been 

 generally received, either as a genus or a subgenus, while Acrosi- 

 phonia appears to have been dropped by the author and forgotten, 

 the earlier name can hardly be displaced, under any system of 

 nomenclature. Whether its rank should be generic or subgeneric is 

 more of an open question ; in the present paper it is treated as a 

 subgenus. Apart from the question of the rank of Spongomorpha 

 and Aegagropila, there is no question as to the extent and limita- 

 tions of the genus Cladophora. 



Cladophora. 



Frond consisting of articulate, branched, monosiphonous filaments, 

 with terminal or intercalary growth. Cells cylindrical or subcylin- 

 drical, plurinuclear, with disk-shaped, parietal chromatophores. 



Sub-genus Spongomorpha. 



Fronds with normal erect filaments, increasing in diameter up- 

 wards, with long terminal cell from which cells are successively cut 

 off below ; these cells continuing to divide, so that the cells in the 

 older parts of the filaments are much shorter than those in the grow- 

 ing tips ; also with descending rhizoidal filaments, and in some spe- 

 cies patent, acute, hooked or curved branches, the older fronds being 

 more or less densely matted together by the descending or patent 

 branches. 



C. ARCTA (Dillw.) KiltZ. 



Kiitzing, Phyc. Germ., p. 207. 



Harvey, Phycologia Britannica, PI. CXXXV ; Nereis Boreali- 

 Americana. part 3, p. 75. 



1 J. G. Ag^ardh, Anadema, Novum Genus Algarum. p. 12. Stockholm, 1848. 



2 Kiitzing, Phycologia Generalis, p. 273, 1843. 



