IV. CHORDARIACE^.— Mbsogloia. 125 



curved or flexuous. In some specimens these forked branches are quite naked ; in 

 others furnished with patent simple or forked ramuli from half an inch to an inch 

 in length ; and in others beset with a multitude of such ramuli, or of more com- 

 pound ones. In these last the frond becomes excessively branched, with all its 

 divisions divaricated and beset with irregular branchlets. When young, the axis is 

 solid, firmly cartilaginous and cellular, but with advancing age the central cells die 

 out, and the stems and branches become fistular, or even somewhat inflated. Such 

 specimens also lose much of their original lubricity, and may readily be mistaken 

 for a different species — or even for a Stilophora, if care be not taken to observe the 

 filaments of the periphery. These filaments afford a tolerably definite specific 

 chai-acter in being slender, with a large terminal cell ; but in individuals of 

 different ages the size of the terminal cell varies considerably. The colour is a 

 greenish olive, paler than in the former species, but becomes dark brown in old 

 age and in drying, in Avhich latter state the plant adheres to paper and shrinks very 

 considerably. 



Plate XI. A. Frond of Chordaria divaricata, the natural size ; Jig. 2, cross 

 section of a young branch; and Ji{/. 3, the same of an older branch, both equally 

 magnified ; fig. 4, a spore and two peripheric filaments, lilghlg magmfied. 



II. MESOGLOIA, Ag. 



Frond cylindrical, branched, cartilagineo-gelatinous, solid, at length partially 

 hollow in the centre, coated with a pile of radiating, horizontal, branched peri- 

 pheric filaments. Axis composed of longitudinal, articulated, anastomosing fila- 

 ments, connected together into a network, which is laxer toward the centre ; the 

 cells of the inner filaments long, those of the outer shorter. Filaments of the 

 periphery rising from the outer layer of axial filaments, moniliform, composed of 

 ellipsoidal cells, fasciculate, frequently dichotomous. Spores obovoid, attached to 

 the base of the peripheric filaments, and concealed among them. 



Plants with the habit and much of the structure of Chordaria, but of a more 

 gelatinous substance and looser texture. In this group I propose to include 

 Myriocladia of J. Agardh, the structure of which does not appear to me to be 

 essentially different from that of ordinary Mesogloice, while the external habit is 

 so similar that even the specific diversity of the species of Myriocladia from species 

 referred by Agardh to Mesogloia is variously held by different authors. Careful 

 analyses of recent specimens in various stages have still to be made ; for though 

 these plants can be tolerably well observed in a dried state, it is not easy in that 

 state to isolate the filaments of the axis so as to show the structure perfectly. For 



