V. CORALLINACE.E. 81 



mass resembles a stony head of cauliflower, or some of the incrustations of similar 

 aspect so often seen in calcareous spar caves. Others are more shrub-like or arbo- 

 rescent, and in others the branches become compressed, or flattened into leafy 

 lobes. In the genus Mastophora, the most leaf-like plants of the Order, there is less 

 carbonate of lime deposited than in most others, and the fronds are proportionably 

 flexible ; they are fan-shaped, with fasti^iate leafy lacinia;, and have a habit very 

 similar to that of some species of Zonaria. All the above varieties of form are 

 found in the sub-order Nulliporea} {Spomjitece, Kiitz). The true Corallines or 

 Corallinece are filiform, somewhat compressed, pinnated or dichotomous, the 

 branches composed of strings of calcareous articulations or internodes, truncated at 

 the upper extremity and rounded at the lower, each articulation connected with 

 that above and below it by a flexible node or joint formed of cellular tissue, in 

 which no calcareous matter is deposited. In the majority, the calcareous inter- 

 nodes are separated by minute flexible nodes, often hidden under the projecting 

 edges of the internode, and only to be seen on close examination. But in some 

 species of Amphiroa the flexible node is elongate, and even occasionally longer 

 than the calcareous internode, the branches of such species looking like a number 

 of beads or bugles, distantly placed on a connecting thread. In some of these 

 latter the surface of the node is occasionally armed with minute calcareous plates 

 or tubercles. The form of the internode varies extremely ; often in the same 

 species ; or even in different parts of the same individual, in which it is common 

 to find the articulations of the stem, the branches and the ultimate I'amuli having 

 distinct forms. In many the internodes are cylindrical ; in others oval or com- 

 pressed ; in others flat and with an irregular outline ; but the most common forms 

 are cordate and cuneiform, the upper angles or shoulders of the internode often 

 extending into ears or horns. 



The fructification is not perfectly ascertained, and the position and affinities of 

 the order are therefore uncertain. It is not without hesitation that I now give the 

 name of four-jointed spore-threads to the little bodies found tufted in the base of the 

 conceptacles, and which in another place (Phyc Brit. t. 201, 222, 252) I have 

 figured and described as zonate tetraspores. If we are to judge of their nature by 

 their aspect, we shall certainly, with Decaisne and other writers, regard them as 

 tetraspores ; but if by the position they occupy within conceptacles formed on the 

 type of those of Polysiplionia, we shall pronounce them spore-threads. If they 

 were not four-parted, they would very closely resemble the spore-threads of a Poly- 

 siphonia ; and they occupy a place exactly similar, being transformations of the 

 same parts of the frond, and similarly protected within conceptacles, whose foi'in 

 and origin are identical with those of the conceptacles in Polysiphonia. So that 

 morphologically speaking, Ave are compelled to regard them as spore-threads. If 

 this be their real nature, it may be worth enquiry whether the supposed tetraspores 

 of Phacelocarpus and ApojMa'a lira not to be regarded as strings of spores, being found 

 lodged within hollow conceptacles, to the walls of wliich they are attached. I am 

 aware that other conceptacles have been described in Phacelocarpus, but after an 

 examination of many specimens I have failed to detect perfect spores within them, 

 and consequently consider them as merely abortive efforts at fructification ; au 



VOL. IV. — AKT. 5. M 



