OP ARTS AND SCIENCES. 119 



inside of this is a circular patch of rounded cells twice as large as 

 the ordinary cells of the wall. So that the basal chamber of the 

 side branch is separated from the chamber of the main branch by two 

 layers of cells. There are a good many more filaments in this species 

 than there are in Champia parvula, and each filament has about seveu 

 cells to a chamber. On each of the filament cells except those piercing 

 the diaphragms there is a bulb-cell, or there may be a pair of them 

 together. The cells that connect the filaments with the cortical layer 

 are sometimes enlarged, and bear bulb-cells similar to those on the fila- 

 ments. The branches spring from a cortical layer directly opposite 

 a filament, as in Champia parvula, and in the one specimen that I 

 examined on this point I found a bulb-cell at the centre of the base of 

 the branch. 



Lomentaria Baileyana is very different from Champia. There are 

 no diaphragms in the frond except across the base of the branches. 

 Inside the cortical layer, which resembles the one in Champia, is a 

 network with rather small meshes, composed of oblong cells whose 

 long axes run more or less obliquely in the direction of their part of 

 the plant. Inside of this network is another, with large meshes, 

 and formed by slender crooked and branched filaments, on which are 

 found occasionally bulb-cells like those in Champia. The filaments 

 seem to come together at the tip in a sort of tuft, in which I can see 

 no regular order. 



I have also examined some dried material of Lomentaria Coulteri. 

 The main stems of this plant are without constrictions and solid, while 

 the small side branches are chambered, and superficially resemble Cham- 

 pia. The whole plant is covered with a cortical layer of small colum- 

 nar cells, well filled with protoplasm, and containing the coloring matter. 

 The bulk of the main stem is of ordinary parenchyma, the cells con- 

 taining but little protoplasm. The chambered branches have a single 

 layer of this tissue lining the cortex, and it also forms the single-layered 

 diaphragms. The filaments in the chambered portion somewhat resemble 

 those in Lomentaria Baileyana, but resemble more closely those in 

 Champia parvula. They plainly converge to a point at the apex of 

 the branch ; but just what the structure is there, the material was in- 

 sufficient to show. 



We have to leave our subject for the present in an unsettled, and 

 therefore rather unsatisfactory condition. In order to get a complete 

 understanding of these hollow-fronded sea-weeds, the development of 

 one or more of them must be traced from the spore to the adult stage. 

 The present paper can, however, lay claim to having added its little to 



