V. CERAMIACE^. 225 



Hab. Generally on rocks, rarely on the stems of the littoral Fuel. Boston Bay, 

 at Beverley, W. H. H. Newport, Prof. Bailey, Mr. Olney, ^c. Squan Beach, New 

 Jersey, Miss Morris, (v. v.) 



Fronds three to six inches long and as much in the expansion of the branches, as 

 thick as hog's bristle at the base, attenuated upwards, terete, not compressed or 

 two-edged, decompound-pinnate ; the larger branches irregularly alternate and of 

 unequal length, the lesser close together, opposite, either of equal length or one of 

 each pair short, the other longer and more compound. The lesser branches are 

 linear-oblong or somewhat obovate in outline, their upper subdivisions being 

 successively longer than the lower ; they are twice or thrice pinnated. All the 

 divisions, except by suppression, are strictly opposite, but towards the extremities 

 one of the opposing pinnae is often imperfectly formed. The pinnules and all the 

 younger pinnas are articulate, composed of a single row of large, quadrate or slightly 

 oblong cells ; they are slightly incurved, of equal diameter throughout, very 

 obtuse, and those along the outer edge of the rachis are generally longest, and are 

 frequently pinnellated at the tips. Tdraspores borne on the tips of the ultimate 

 pinnules, at first containing four sporules, afterwards eight or a larger number, 

 when they resemble favellte. Colour a brownish purple, rather dark ; a clear 

 purple-lake under the microscope. Substance soft. In drying, it closely adheres to 

 paper. 



A smaller and softer plant than any of the preceding and readily known by its 

 articulated pinnules. 



V. CROUANIA. J.Ag. 



Frond filiform, gelatinous, nodoso-moniliform, alternately decompound, consisting 

 of an articulated, monosiphonous primary filament (or axis) emitting at the nodes 

 densely whorled, minute, dichotomo-fastigiate, gelatinous, free ramelli. Favellce 

 near the ends of the branches sub-solitary, affixed at the base of the whorled ramelli 

 and covered by them, containing, within a hyaline periderm, numerous roundish 

 spores. Tetraspores fixed at the base of the ramelli, partly hidden by them, 

 roundish, triangularly parted or transversely bi-parted. 



Very flaccid, gelatinous Algae of small size with moniliform branches, resembling 

 in habit the species of the fresh water genus Batrachospermum. In artificial 

 character they nearly coincide with the species of Halurus, but differ essentially in 

 the position of the fructification, and in the substance of which the frond is com- 

 posed. The young branches are nearly cylindrical, the whorled ramelli forming a 

 scarcely interrupted periphery. As the frond increases in age, the whorls are 



VOL. IV. — ART. 5. G G 



