90 SPH^ROCOCCOIDEiE. v. 



Atlantic coast, indeed, Nitophyllum is scarcely more than represented. In South 

 America, especially among the indented shores of Terra del Fuego and the islands 

 and channels near Cape Horn both these genera abound, as they also do in New 

 Zealand and Van Dieman's Land. Nitophyllum venosum is one of the largest and 

 most splendid of South African Rhodosperras, its brilliant fronds being sometimes 

 two or three feet in breadth. Delesseria Leprieurii, which is found in the Hudson river 

 at "VVestpoint, sixty miles from the sea, and in the estuaries of several rivers of the 

 Southern States, was first discovered in the Sinnaraar river, Cayenne ; and has been 

 also found in New Zealand ; a singularly sporadic distribution. Delesseria querci- 

 folia of the southern hemisphere is scarcely distinguishable from B. simiosa of the 

 northern ; the southern D. crassinervia chiefly diifers from the northern D. Hypo- 

 glossum by the thickness of its midrib ; while D. ruscifoUa is found in both 

 northern and southern hemispheres. It is curious that Hymenena and Botryo- 

 glossum are found in South Africa and California, the latter genus also at 

 the Falkland Islands. GrinnelUa is exclusively American, and is one of the most 

 beautiful and characteristic Algae of the Atlantic coast. Sphceivcoccus is European. 

 Several genera are exclusively from the Southern Ocean, many being Australian. 

 Gracilaria is found from the tropics to very high latitudes at either side of the line, 

 and G. confervoides and G. nndtipartita are instances of cosmopolitan species. 



Of economical species the only ones deserving notice are the Gracilarice, many 

 of which are largely used in India and China, both for food and in the preparation 

 of glues and varnishes. G. lichenoides or Ceylon moss is a common ingredient in 

 soups and other compound dishes in the East, and is even exported to Europe for 

 similar purposes. It may also be made into jellies and blanc-manges, and is said to 

 be better than Carrigeen ( Chondrus crispus) for all the uses to which that plant is 

 applied. All the Gracilarice readily boil down into a gelatine, and probably are 

 nearly equally valuable. 



SYNOPSIS OF THE NORTH AMERICAN GENERA. 



Tribe 1. DELESSERiEiE. Frond membranaceous, leaf-like ; the surface cells 

 tabular, polygonal, of large size. Spore-threads radiating in a circle from a de- 

 pressed, basal placenta. Tetraspores contained in definite sori. 



* Fronds symmetrical^ midribbed. 



I. Grinnellia. Conceptacles scattered over the membrane. 



II. Delesseria. Conceptacles formed in the midrib, or in a lateral vein. 



Fronds unsymmetrical, ribless or obsoletely ribbed, or traversed by irregular 



branching veins. 



III. BoTRYOGLOSsmi. Frond thickened in the middle, obsoletely midribbed ; the 

 rib broad, vanishing towards the end of the laciniae. 



