V. RHODOMELACEJ:. 19 



V. CHONDRIA. J. Ag. ref. 



Fronds filiform, cartilaginous, pinnately decompound, opaque, coated with small 

 polygonal, irregulai'ly placed cells, ylj-/*' articulated, polysiphonous. ItarnuU club- 

 shaped, very much constricted at their insertion, obtuse or sub-acute, transversely 

 striolate. Conceptades ovate, perforate, sessile or pedicellate on the ramuli, con- 

 taining, within a cellular pericarp, a tuft of pear-shaped spores on simple funiculi 

 radiating from a basal placenta. Tetraspores tripartite, crowded irregularly in the 

 club-shaped ramuli, formed from the endochrome of the radiant cells. 



Frond of a cartilaginous or subgelatinous substance, soon decomposing in fresh 

 water, and generally closely adhering to paper in drying, filiform, more or less 

 regularly pinnately decompound, but not strictly distichous. Branches, and their 

 subsequent decompositions, simple, virgate, attenuated at the base and apex, set 

 with more or less abundant lateral, scattered, spirally inserted simple ramuli, 

 which are always very much constricted at the base, and either abruptly truncate 

 or attenuate at the apex. The surface of the frond is composed of small irregular 

 oblong cells, through Avhich the internal articulated axis is rarely visible, except in 

 the ultimate ramuli of some species. This axis is formed of four or five large 

 oblong cells of equal length, disposed in a radiant manner round a central cell. 

 Some species are rosy purple, staining fresh water carmine ; others in steeping give 

 out a brown fluid of offensive odour, and stain paper a fulvous brown ; others are 

 dark purple, or tinged with green. Conceptades generally on the sides of the 

 ramuli, mostly ovate and subsessile. Tetraspores lodged within the axial cells of the 

 ramuli, one or more in each cell, large, irregularly crowded near the extremities. 



A large genus, the species of which until recently have been arranged among the 

 Laurencia;, from which position Prof J. Agardh has very properly separated them. 

 Their agreement with Laurencia (typified by L. pinnatifida and its allies) is more 

 in external habit than in structural character. They differ especially in the articu- 

 lated polysiphonous axis, a character by which they are associated with the lihodo- 

 Tiielacece. Besides the North American species described below, I possess some 

 imperfect specimens from Key "West, which I have not been able to refer to their 

 proper place ; and probably other new species may remain to reward a diligent 

 search on the shores of the Southern States. 



1. Chondria sedifolia ; frond alternately much branched ; branches patent, decom- 

 pound, beset with short, spindleshaped, scattered or tufted ramuli much contracted 

 at the base, and sub-acute or obtuse at the apex ; conceptades ovate, sessile on the 

 ramuli. (Tab. XYIII. G.) 



IIab. Key West, Mr. Binney, W. H. IL, Dr. Blodgett, (33, 34, &c.) Prof. Tuomey, 



(45, 52, &c.) (v. V.) 



d2 



