V. CRYPTONEMIACE^. 161 



XVI. Chrysymenia. Conceptacles half immersed in the frond, obtuse or acute, 

 containing a very dense, depressed-spherical mass of minute spores attached 

 to a basal placenta. Frond compressed or inflated, hollow or subsohd. 



f f Sporiferous nuclei immersed in the frond. 



XVII. Haltmenia. Frond flat or compressed, dichotomous or pinnate. 



fff Nuclei unknown (station in the Order doubtful.) 



XVIII. Halosaccion. Frond membranaceous, tubular or inflated ; the walls of 

 the tube composed on the inside of roundish polygonal cells ; toward the 

 surface of minute, oblong, vertically seriated cellules. 



Tkibe 6. NEMASTOMEiE : Fronil cartilaginous, coriaceous or gelatinous, wholly com- 

 posed of filaments ; the inner stratum longitudinal, interlaced, the outer ver- 

 tical to the surface and dichotomo-fastigiate. 



* Nuclei lodged in terminal, pod-like branches, 



XIX. FmiCELLARiA. Frond terete, dichotomous, fastigiate. 



** Nuclei lodged in terminal, wart-like excrescences. 



XX. AcROTTLUS. Frond terete, simple or forked, cartilaginous. 



*** Nuclei dispersed through the unaltered frond. 

 f Frond compressed or flat, solid, and of very compact substance. 



XXI. Prionitis. a stratum of roundish cells interposed between the medullary 

 and peripheric strata, which are composed of filaments. 



XXII. Grateloupia. Destitute of intermediate stratum ; medullary stratum of 

 densely interwoven filaments ; periphery of vertical, moniliform, closely 

 packed filaments. 



f f Frond tubular, membranous or gelatinous. 



XXIII. Cateneixa. Frond membranous, moniliform ; constricted at regular 

 intervals as if jointed. Nuclei in minute, contracted ramuli. 



XXIV. Gloiosiphonia. Frond gelatinous, filiform. 



VOL. IV. — ART 5. ^ 



