THE MARINE ALG^E OP NEW ENGLAND. 75 



INSUFFICIENTLY DESCRIBED SPECIES. 



E. Landsburgii, Harvey, Ker. Am. Bor., Vol. I, PI. 12 d. 



Halifax, N. S. 



E. Hooperi, Harvey, 1. c., PL 12 e. 



Greenport, L. I. (?) 



E. Dietzi^e, Harvey, 1. c., p. 144. 



Greenport. 



Family SPHACELARIE^E. 



Fronds branching, polysiphouous, terminating in a large apical cell, 

 often with a cortex formed of deusely interwoven rhizoidal filaments ; 

 fructification same as in Ectocarpece. 



Corticating cells wanting or confined to the base of the frond. 



Sphacelaria. 

 Main branches corticated throughput. 



Branches opposite, distichous Chcetopteris. 



Branches whorled Cladostephus. 



SPHACELABIA, Lyngb. 



(From ofyaKE^oq, gangrene, referring to the tips of the branches, which are black and 



shriveled Avhen dried.) 



Fronds olive-brown, filamentous, branching; axis and branches ter- 

 minated by a large apical cell, from which, by transverse, longitudinal, 

 and oblique divisions, a solid frond is formed whose external surface is 

 composed of rectangular cells arranged in regular transverse bands ; 

 hairs slightly developed or wanting; rhizoidal filaments few, rarely 

 interwoven so as to form a false cortex; unilocular and plurilocular 

 sporangia spherical or ellipsoidal, on short pedicels ; non-sexual repro- 

 production by peculiarly modified branches called propagula. 



The old genus Sphacelaria was divided by Kiitzing into a number of genera, and his 

 views have been adopted by many recent writers, especially in Germauy. In Stypo- 

 caulon and Halopteris the branches arise from lateral divisions of the apical cell itself, 

 while in Sphacelaria proper, Chcetopteris and Cladostephus, the branches arise from cells 

 below the apex. Whether this difference in the apical growth can be considered a 

 generic mark is not altogether certain, and there hardly seems to be sufficient ground 

 for separating Halopteris from Sphacelaria, and a number of writers, among whom 

 may be named Harvey and Le Jolis, even include Stypocaulon. Cladostephus is mark- 

 edly distinct ; and Chwtopteris, which differs from Sphacelaria principally in the corti- 



Giraudia spiiacelarioides, Derb. & Sol., a common Mediterranean alga, which 

 occasionally occurs as far north as the Scandinavian coast, may perhaps be found ou 

 our shore. It resembles a small Sphacelaria, but its growth is trichothallic, not from 

 an apical cell, and the small unilocular sporangia cover the frond in deuse patches. 

 The plurilocular sporangia resemble those of some Ectocarpi, and are found at the base 

 of the plant according to Areschoug. 



