86 Universitij of California Publications in Bolanij [Vol. 6 



applied to it, running longitudinally downwards, are very slender 

 filaments. These filaments vary in abundance in the different species 

 and in flattened species are more abundant just within the margins. 

 This layer will be referred to as the "corticating layer." In the 

 center of the frond is an axis of intertwined longitudinal filaments of 

 two sorts, coarser and finer. The coarser filaments originate from the 

 apical meristem. the finer are corticating filaments. This axial strand 

 varies in coarseness even in the same species, but in different species 

 the difference may be sufficient to attract attention. This happens 

 when it is invisible in pressed specimens of one species and visible 

 in others. Some discussion has arisen in this connection (cf. Harvey. 

 1846. pi. LXIX, J. G. Agardh, 1851, p. 423, Bornet et Tlmret, 1876. 

 p. 20, etc.) and it is not possible even yet to separate species definitely 

 according to Avhether the axis shows in the dried (and pressed) speci- 

 mens or not. Something, however, may be said, as will be seen below 

 in the discussions under the separate species recognized in this paper. 



Antheridia and cystocarps are known in Sciiiaia, but as yet no 

 tetrasporangia have been detected. 



The antheridia of Scinaia furcellata have been briefly described by 

 Bornet and Thuret (1876, p. 20) as forming very small bouquets 

 disseminated between the peripheral cells of the frond, which renders 

 them difficult of detection. Antheridia have been seen in almost all 

 of the species of Scinma described below and in all species of Gloio- 

 pJiloea and of Pseudoscinaia. In all the species of Scinaia and Pseudo- 

 scinaia they occur scattered single, or in small groups, and probably 

 always on the same plant with the cystocarps. In Gloiophloea the 

 antheridia cover extensive areas, either on the same plant with the 

 cystocarps or on separate plants. They occur singly or in twos on 

 longer or shorter supporting cells which grow out between the utricles 

 in all three genera. 



Although it is not so stated by any authority, so far as the writer 

 is aware, Scinaia furcellata is monoecious and bears the antheridia 

 singly or in small fascicles, as Bornet describes, between the colorless 

 epidermal cells. Possibly all the species of Scinaia are monoecious, 

 but in a tm species described below the w^riter has not been able to 

 demonstrate this to his own satisfaction because of the lack of 

 abundant material. The writer suspects that a certain group of species, 

 in which the colored cells in the epidermal layer are scanty, may 

 po.ssibly be dioecious. Farther discussion may be left until the con- 

 ditions in the individual species are taken up. 



