WEBER-VAN BOSSE—MARINE ALG A 299 
thick, the transverse membranes of the succeeding segments within are plainly visible, 
owing to the fact that the central strand consists of a large number of cells of equal 
length. The segments are short, and this fact gives, whenever the apex of a shoot is 
pushed aside, the impression that the main axis is divided into three branches. Careful 
examination will, however, show that this impression is erroneous, being brought about 
by the displaced shoot, its first branch—the new shoot—and its second branch standing 
very close together, owing to the short segments and the congenital growth of the first 
two segments. 
My plants are barren: J. Agardh, however, described the stichidia, which he stated 
were like those of Dasya and bore verticillately developed tetraspores partially uncovered 
on the outside. 
Amphisbetema bas received its name* on account of the difficulty experienced in 
assigning to it its true systematic position. It has characters in common with severai 
genera of Rhodomelaceze and also with Melanothamnus, Born. et Falk., a genus of 
uncertain position so long as the organs of fructification remain unknown. 
With Streblocladia, Amphisbetema agrees in the regular alternating mode of mono- 
podial and sympodial growth; with Melanothamnus and Endosiphonia in the numerous 
secondary pericentral cells of equal length; with Heterosiphonia in the dorsi-ventral 
organization of its branches ; and with Dasya in the structure of the stichidia. 
The association of all these characters in one genus makes me inclined to consider 
Amphisbetema as an old form of Rhodomelaceze which existed before the genera that 
have now developed one or more of the characters—in our new genus still blended 
together—in their own special way and to the exclusion cf the other characters. 
Dicryurws, Bory. 
1. DicTyURUS PURPURASCENS, Bory. 
Bory de St. Vincent, in Bélanger, Voy. Indes orient. p. 170. 
Falkenberg, Die Rhodomelaceen, 1901, p. 675. 
De Toni, Syll. Alg. vol. iv. sect. 111. 1903, p. 1173. 
Saya de Malha, 55 fms.; dry specimen. 
Coetivy, reef; drv specimen and in alcohol (fragment). 
Cargados Carajos, 30 and 47 fms.; dry specimen and in alcohol. 
Ayirante, 30 fms. ; in alcohol. 
Chagos Archipelago, Salomon Atoll, 22 fms.; in alcohol. 
Distribution. Cape Comorin ; Coast of India; Mauritius; Ceyion; Malay Archi- 
pelago. 
Fam. CERAMIACE. 
GrirFirusia, C. Agardh. 
1. GRIFFITHSIA spec. 
Anmirante, 20-25 fms.; in alcohol. 
Only a small fragment, but with the characteristic tetraspores of the genus. 
* apudeoPirnia, controversy, a point in dispute. 

