THE MARINE ALG^ OF NEW ENGLAND. 181 



Fronds thin, orbicular, becoming confluent, distinctly zonate ; hetero- 

 cysts present, basal cells elongated-rectangular, cortical cells semicircu- 

 lar or triangular seen from above; tetrasporic conceptacles small, hemi- 

 spherical, orifice not plainly ciliate; tetraspores four-parted ; antheridia 

 and cystocarps ? 



On Fuctts vesiculosus. 



Wood's Holl, Mass ; in all parts of the world. 



Although ouly one locality is mentioned, the species probably occurs throughout 

 our limits. It is distinguished from the last by the shape of the conceptacles and the 

 absence of a circle of cilia around the orifice. The fronds are larger and more- fre- 

 quently orbicular, although scarcely thicker than in If. Lejolisii. In both species the 

 calcareous incrustation is somewhat farinaceous as compared with the following, in 

 which the incrustation is smoother and solid. M. membranacea, Lam.x. related to M. 

 farinosa, but destitute of heterocysts and having tetrasporic conceptacles with several 

 orifices, is to be expected on algae of our coast. 



M. pustulata, Liim.x. (31. pustulata, Phyc. Brit., PI. 347 d ; Eosa- 

 noff, 1. c, PI. 4, Figs. 2-8.) 



Fronds rather thick, circular, becoming reniform or orbicular, indis- 

 tinctly zoned ; heterocysts wanting, basal cells elongated vertically, cor- 

 tical cells squarish; conceptacles large, hemispherical, orifice naked; 

 tetraspores four-parted. 



Probably common on the larger algae along the whole coast, but being undistinguish- 

 ablo from the next species when sterile, one cannot be sure of the species unless it is 

 in fruit. The tetraspores of M. pustulata are zonately four-parted, while those of M. 

 macrocarpa are merely two-parted at maturity. In both species the fronds are rather 

 thick and solid and do not crumble, as in the two preceding species, and the orbicular 

 shape is preserved for a longer time. 



M. macrocarpa, Eosanoff. (31. macrocarpa, 1. c, p. 74, PI. 4, Figs. 

 2-8 and 11-20.) 



Fronds as in M. pustulata ; tetraspores large, two-parted. 



On Chondrus. 



Gloucester, Mass. ; Europe. 



b. Species rather large, growing on stones and shells, cortical stratum 

 well developed. 



M. Lenormandi, Aresch. (Lithophyllum Lenormandi, Eosanoff, 1. c, 

 p. 85, PI. V, Figs. 1G, 17 ; PI. VI, Figs. 1, 2, 3, 5.) 



Fronds saxicolous, closely adherent to the substratum, suborbicular, 

 becoming squamulose-imbricate, slightly zonate, margin crenate, lobed ; 

 tetraspores four-parted, in compressed, hemispherical conceptacles, with 

 numerous orifices ; antheridia and cystocarps ? 



On stones. 



Gloucester, Mass. ; Europe. 



Apparently common in many places, but fruiting specimens were only collected at 



