532 CERAMIACEAE. 



orate below; nodal bands of corticating cells very narrow, slightly protuberant, 

 mostly only one cell wide (high), the cells with their longer axes (20-40 /u) 

 usually directed lengthwise of the filament, about four cells measuring the 

 diameter of the filament, irregular smaller cells sometimes forming an imper- 

 fect second (upper) row; tetrasporangia solitary or 2 or 3 at a node, mostly 

 secund along the outer side of the filament, occasionally subverticillate, 50-65 ti 

 in maximum diameter, the primary wholly naked, the secondary (formed by 

 regeneration) subtended by 2-4 small sterile cells and thereby often much 

 exserted or substipitate, the tetraspores somewhat tetrahedrally disposed. 



Type from a pond at "Walsingham, having subterranean communication 

 with the sea, (Hoive 99, in herb. N. Y. Botanical Garden). 



Ceramium leptosonum is related to C. hyssoideum and the plants currently 

 known as C. tenuissimum, but seems to be amply distinct in having ordinarily 

 only a single row of corticating cells at the nodes, these cells nearly always 

 elongate in the direction of the filament, and in the naked primary tetra- 

 sporangia. In the narrow nodal zones, the regenerating tetrasporangia, and 

 the rather persistent coloring of the protoplasts of the large internodal cells, 

 the species is slightly suggestive of Ceramothamnion Codii, from which it is 

 easily distinguished by the apparently non-repent habit, the dichotomous 

 stouter and taller filaments, the usually single instead of double row of nodal 

 cells, which are also more elongate, the relatively smaller naked primary 

 tetrasporangia, etc. Ceramium cruciatum and C. tenuissimum also sometimes 

 show persistently colored fibrillar chromatophores in the internodal cells. In 

 soaked-out dried specimens, the nodal cells often appear to be more numerous 

 than they really are, owing to the segregation of chromatophores or to the 

 purely optical cutting of these cells by the nodal diaphragm. The tetraspores 

 sometimes germinate in situ, giving rise to small proliferations. The species 

 is apparently endemic. 



Ceramothamnion Codii Richards, is a small plant epiphytic on species of 

 Codium along the South Shore and on Cooper 's Island. It creeps along the 

 surface of the Codium, sending down rhizoids among the utricles of its host and 

 sending up erect filaments less than a line high and gV" sV o^ ^ li^^ i^ diameter, 

 which are unbranched except in connection with the formation of the so-called 

 polysporangia, the apices remaining straight and erect. The uncorticated 

 internodal cells are mostly 1^-3 times as long as broad, and show persistently 

 colored fibrillar chromatophores, somewhat as in Ceramium cruciatum and C. 

 leptozonum. The nodal bands of corticating cells are 2 (3) cells wide (high), 

 these cells with their longer axes variously directed, 3 or 4 cells measuring the 

 width of the filament. The tetrasporangia are solitary at the nodes, subsecund, 

 broader at maturity than the filament, subtended in the basal half by an 

 involucral cup of sterile cells, and regenerating, the spores arranged in decus- 

 sate pairs. Antheridia form compact, small-celled, subglobose, sometimes con- 

 fluent enlargements of the nodes of different individuals from those that bear 

 the tetraspores. Supposed polysporangia or parasporangia, of non-sexual 

 origin, irregularly ovoid, subglobose or ellipsoid, occur on the erect filaments, 

 usually in pairs, and subtended by three or four short branches similar in struc- 

 ture to the filaments. Ceramothamnion appears to differ from Ceramium in 

 scarcely anything but in the occurrence of alleged polysporangia of non- 



