VALONIACEiE. 
41 
Order XXL— VALONIACEJE. 
Valoniece , in part , Kiitz. Sp. Alg. p. 507. Anadyomenece , Dictyospheriece, and 
part of Codiece, Kiitz. 1. c. Siphoneoe , m. part , Awc£. aA'or. 
Diagnosis. Green marine Algae, naked or encrusted with carbonate of lime, with 
fibrous roots. Frond polymorphous, formed of large vesicated cells filled with watery 
endochrome ; either consisting of a single cell, or of several united into filaments, or 
into net-works or membranous leaf-like expansions. 
Natural Character. Root in most cases well developed, and consisting of a plexus 
of tough fibres, forming a mat, and either penetrating the sand or grasping firmly to 
the rock or stones on which the plant grows. Frond very variable in form, and in 
complexity of structure. In Yalonia the whole frond, in some species, consists of a 
single vesicated cell, which is often of large size, upwards of an inch in length, and 
three-quarters of an inch in diameter, filled with a thin, watery endochrome. In other 
species of that genus, several such cells are strung together so as to form confervoid 
branching filaments. In Dictyosphceria , a number of large globose cells cohere toge- 
ther in a single stratum, and thus form a tessellated or honey-combed membrane. In 
Anadyomene , the membranous expansion is formed in a different manner, namely, by 
the lateral cohesion and anastomosis of a branching filament ; and in Microdictyon , a 
network is formed in a similar way, the difference from Anadyomene being, that the 
branches of the generating filament stand apart, leaving open spaces between their 
anastomosing rarnuli. A further advance in structure occurs in Penicillus , where the 
frond has a dendroid habit ; the trunk of the treelike body being composed of branch- 
ing, unicellular filaments like those of a Codium , and the head of confervoid, articulated 
filaments like those of Yalonia. This spongy caudex, or trunk, appears to me to be 
merely an exaggeration of the rooting processes, common to most plants of the family. 
A more definite stipes, or true stem, is found in Chamcedoris , Apjohnia , and Struvea , 
the most highly organised genera of the Order, and those which connect it with the 
Dasycladece. In these the stipe is monosiphonous, and is developed nearly to its full 
size before any part of the capitulum makes its appearance. In the early stage these 
plants are not to be known from the simple Yalonice , and like them consist of a single 
cell rising from a branching root. 
In this description of the fronds of the Order I omit the curious plant which will be 
G 
