V. CRYPTONEMIACE^. 185 



late and minutely curled margin. Sometimes the margin is quite entire and fiat. 

 The primary lamina is frequently proliferous from the summit or disc of its lobes 

 with similar secondary fronds ; and these in large specimens bear tertiary ones, the 

 whole resulting in a broadly flxn-shaped general outline. Colour a clear, deep lake- 

 red, changing to greenish-white in fresh water. Substance rigidly membranaceous. 

 It does not adhere to paper. The medullary stratum is formed of densely inter- 

 woven filaments ; outside which are several rows of coloured, polygonal cells, the 

 innermost being large, the rest successively smaller ; the superficial ones very 

 minute. 



XV. CHYLOCLADIA. Gh^ev.—J. Ag. ref. 



Frond terete or sub-compressed, (rarely nodoso-articulate,) alternately or pin- 

 nately-decompound, tubular ; the tube empty, or traversed by a few slender, longi- 

 tudinal filaments ; the periphery formed of several rows of roundish-angular cells, 

 successively smaller to the surface. Concepiades external, conical or apiculate, at 

 length pierced by a pore, containing a nucleus enclosed in a hyaline mucous enve- 

 lope, surrounded by a net-work of anastomosing filaments ; the spores " originating 

 in the cells of filaments radiating from a placenta, at length" numerous, massed 

 together. Tetraspores triangularly parted, dispersed among the superficial cells of 

 the branches. 



I adopt this genus as now, by Prof. J. Agardh, restricted to the Fucus clavellosiis, 

 Turn. Hist. t. 30, and its allies. Among these latter, however, I place the F. arti- 

 cidafus, Lightf notwithstanding its difference of habit, because, as correctly pointed 

 out by Dr. Greville, (Alg. Brit. p. 114) the structure of its conceptacle, both ex- 

 ternally and internally, is similar to that of F. clavellosus. I have not verified the 

 mode of development of the spores as given in the generic character on Prof 

 Agardh's authority ; the specimens which I have at hand exhibiting only the nu- 

 cleus as it eventually becomes, namely, a cluster of disorderly spores contained 

 within a mucous integument, closely resembling a " favella." 



1. Chyloclabia Baileijana ; fronds tubular, cylindrical, densely tufted, short, 

 irregularly much branched ; branches (mostly arching) divaricated, secund or 

 scattered, their lesser divisions mostly secund, and furnished with a few secund, 

 spindle-shaped ramuli tapering to the base and apex. C. divaricata, Harv. MSS. 

 {not of J. Ag.) (Tab. XX. C. Fig. 1.) ^jiUformis ; very slender, elongate, with 

 longer and less arching branches. (Tab. XX. C. Fig. 2) 7. ? valida ; frond robust, 

 firm, sometimes with arching, unilateral ramification ; sometimes sub-alternately 

 pinnate. 



VOL. rv. — ART 5. 2 ^ 



