V. CRYPTONEffiACE^. I89 



tuft of dichotomous branches spring, making the habit very bushy. The axils are 

 singularly rounded, the lacinite very widely spreading, and the apices remarkably 

 obtuse. The frond is tubular, but strongly compressed and almost flattened. Its 

 walls are thin ; the inner stratum composed of polygonal, inflated, empty cells of 

 large size ; the outer of very minute, coloured cellules, set in densely packed, 

 vertical filaments. Conceptacles plentifully scattered over all the lower lacinias, be- 

 tween hemispherical and conical, prominent. Tetraspores dispersed through the 

 superficial cells of distinct plants. Colour^ a clear, rosy red, becoming browni.sh in 

 drying. Substance soft and lubricous, full of juice. It adheres closely to paper in 

 drying. 



This is nearly related to the ]\Iediterranean C. dlchofonm, J. Ag. ; but appears, 

 judging by the description, to diflPer in some respects. It has much of the external 

 aspect of some varieties of Halymenia I'lgulata^ whence our specific name. 



Plate XX. A. Fig. 1. Chrysyisienia halymenioides ; the natural size. Fig. 2, 

 transverse section of a lacinia, cutting through three conceptacles ; fig. 3, portion of 

 the surface, viewed vertically -^fig. 4, section of the wall of the frond with immersed 

 tetraspores ; fig. 5, tetraspores ; fig. 6, section of a conceptacle ; fig. 7, nucleus from 

 the same -jfig. 8, spores ; the latter figures more or less highly magnfied. 



Sect. 2. Crtptarachne ; frond flat.,compressed or cyUndrical., siib-solid; the medullary 

 stratum composed of interlaced., anastomosing^ branching filaments. 



3. Chrtstmenia (Crtptarachne) Agardhii ; frond gelatino-membranaceous, flat, 

 dichotomously cleft, lacinias cuneate at the base, tapering to the extremity, undu- 

 late, unequally eroso-dentate at the margin ; the marginal processes sometimes 

 lengthening into linear lobules ; conceptacles acuminate, scattered over the lacinisB. 

 (Tab. XXX. A.) 



Hab. Thrown up from deep water, Key "West ; rare, W. H. H. (v. v.) 



Frond six or eight inches long, as much or more in expansion of the lacinia?, 

 having a wide, cuneate base, one to two inches long and an inch and half broad, 

 at once dividing into several lacinire, in a somewhat palmate order. These 

 laciniaB are simple or forked, or palmatifid, cuneate at the base, about an inch wide 

 at the widest part, tapering to both ends, undulate, with the margin rarely quite 

 entire, more commonly eroso-denticulate. Marginal teeth horizontally patent, very 

 unequal in size, sometimes mere processes a line or two in length, sometimes half 

 an inch long and a line broad. Conceptacles scattered over the lacinite, rather 

 prominent, conical, with the orifice very prominent and slightly oblique. The 

 medullary stratum consists of a dense web of branching and anastomosing fila- 

 ments ; the intermediate of several rows of empty cells, of which the inner are very 

 large, the rest successively smaller ; the cortical of very minute, coloured, seriated 

 cells, in two or three vertical rows. Colour, a pale rose-red, lading and becoming 



