CRYPTONEMIACE.E. 173 



VIII. CONSTANTINEA. Post, and Eupr. 



Frond caulescent, branched ; branches sub-terete, expanding into camoso-coria- 

 ceous, flat, definite laminte, composed of three strata of cells ; the medullary stratum 

 of sparingly anastomosing, interwoven, articulated filaments ; the intermediate of 

 rounded cells ; the cortical of very minute, coloured cellules. Conceptacular nucleus 

 immersed in the substance of the leaves, consisting of numerous nucleoli, each sur- 

 rounded with a gelatinous limbus, and containing a mass of minute spores. 2'etra- 

 spores lodged in external warts (nemathecia), oblong, zonate. 



Nearly related to the preceding genus in artificial character, but differing in the 

 position of the tetraspores, and very dissimilar in external form. Instead of 

 vao^uely shaped, stemless fronds, we have here a regularly branching frond, fur- 

 nished, from its earliest age, with a distinct stem. At first the stem is simple, 

 bearing at its summit a peltate or reniform lamina : by a renewed growth the stem 

 pushes onward through the base of the first leaf (which thus becomes perfoliate or 

 amplexicaul to the new stem) and forms a new leaf at its summit ; and so the frond 

 lengthens, new leaf-bearing internodes continually rising through the bases of the 

 older leaves. After a while they spring in pairs from each leaf-base, and thus the 

 branching becomes normally dichotomous ; but as one internode of the fork is often 

 abortive, old specimens are frequently irregularly decompound. 



Three species of this curious genus are known ; two of them confined to high 

 latitudes in the Pacific Ocean ; the third to very deep water in the Mediterranean 

 Sea, having been dredged by Prof. Edwd. Forbes in 50 fathoms. 



1. CoNSTANTiNEA Sitchensis, Post, and Rupr. ; "stem terete, branched, annulated; 

 internodes separating the rings four times as long as their diameter ; branches ex- 

 panded at the summit into an orbicular, peltate, entire lamina." Post, and Pupr. 

 Illiistr. p. 18, t. 40, /. 88. J. Ag. Sp. Alg. 2, p. 295. Neurocaulon Sitchense, Kiitz. 

 Sp. Alg. 2). 744. 



Hab. Isle of Sitcha, Russian America, 



I have seen no specimens of this rare and singular Alga. 



