188 CRYPTONEMIACEiE. v. 



tertiaries strongly constricted at the base, tapering to the apex, springing without 

 order from all sides, and from the apex, of the primary frond. 



Hab. Key West, Florida, rare, W. H. H. (v. v.) 



The full-grown, compound frond is eight or ten inches long or more, and nearly 

 as much in the expansion of the branches. It originates in a simple, saccate, 

 oblong frond, one to two inches long and about half an inch in diameter, rising 

 from a short, cartilaginous stipes, one to two lines long. This primary sac throws 

 out very irregularly, from its sides and apex, numerous secondary sacs of equal 

 breadth, but generally of greater length, thi'ee to four inches long, strongly con- 

 stricted at the base, or rather minutely stipitate, linear-oblong or somewhat obovate 

 and obtuse. These sacs of secondary order, in their turn give off tertiary sacs, 

 Avhich are generally a quarter inch in diameter, more fusiform than the secondary 

 ones, tapering to the apex, and bearing other smaller, more tapering, irregularly set, 

 sac-like ramuli. In large specimens these latter bear others, and thus the frond 

 continues to become compound by successive proliferous repetitions of sac-like 

 branches. Substance delicately membranaceous, somewhat gelatinous within. The 

 walls are composed of an inner row of large, empty cells, defended externally by 

 two or three rows of minute, polygonal, coloured cellules. Tetraspores abundantly 

 scattered through the cells of the outer coating. Colour, a delicate, rosy-red. In 

 drying, it closely adheres to paper. 



This plant so much resembles some varieties of Halymenia ligulata, that I had at 

 first mistaken it for one of the forms of that sportive species, nor was it till a trans- 

 verse section assured me that it belonged to a different genus, that I discovered ray 

 error. On more closely examining the specimens, an external character is readily 

 found in the ramification ; the present species, though it eventually becomes ex- 

 cessively compound, being constituted of numerous series of perfectly simple frond- 

 lets growing one on the other, and never, that I have seen, forking, as do the ramenta 

 of Hal. ligulata. Under the microscope, the different structure of the two plants is 

 very obvious. 



2. Chrystmenia halymenioides ; frond compressed, broadly linear, cuneate at the 

 base, dichotomous, fastigiate ; the axils rounded, and the lacinise divaricated, very 

 obtuse ; conceptacles hemispherical, prominent, scattered. (Tab. XX. A.) 



Hab. ThroAvn up from deep water. Key West, very rare, W. H. H., Dr. Blod- 

 gett. (v. V.) 



Root scutate. Fronds one or more from the same base, three to four inches long, 

 a quarter to half an inch wide in the widest part, rising from a slender, filiform 

 base, rapidly widening upwards to the first fork ; thence broadly linear and repeat- 

 edly and pretty regularly dichotomous. Sometimes from a wounded part a dense 



