DICTYOTACE.E. 35 



SYNOPSIS OF THE BRITISH GENERA. 



* Root coated with woolly fibres. Frond flat. 



I. CUTLERIA. Frond ribless, irregularly cleft. Sori dot- 



like, scattered. Spores pedicellate, containing eight 

 sporules. [Plate 6, A.] 



II. HALISEEIS. Frond dichotomous, with a midrib. [Plate 



6,B.] 



III. PADINA. Frond ribless, fan-shaped, concentrically 

 striate. Sori linear, concentric, bursting through the 

 epidermis. [Plate 6, C.] 



IV. ZONARIA. Frond ribless, lobed, concentrically striate. 

 Sori roundish, containing spores and jointed threads. 

 [Plate 6, D.] 



V. TAONIA. Frond ribless, irregularly cleft, somewhat 



fan-shaped. Sori linear, concentric, superficial, alter- 

 nating with scattered spores. [Plate 7, B.] 



VI. DICTYOTA. Frond ribless, linear, dichotomous. Sori 

 roundish, scattered, bursting through the epidermis, 

 or (on distinct individuals) scattered spores. [Plate 7, A.] 



** Root a minute, naked disk. Frond cylindrical, branched. 



VII. STILOPHORA. Spores concealed among moniliform 

 threads, which are collected into convex, wart-like 

 sori. [Plate 7, C.] 



VIII. DICTYOSIPHON. Spores irregularly scattered, solitary 

 or in dot-like sori. [Plate 7, D.] 



IX. STRIARIA. Spores in dot-like sori., ranged in trans- 

 verse lines. [Plate 8, A.] 



*** Root a minute, naked disk. Frond cylindrical or flat, unbranched. 



X. PUNCTARIA. Frond flat, leaf-like. [Plate 8, B.] 



XI. ASPEROCOCCUS. Frond membranous, tubular, either 

 cylindrical or compressed. Spores in dot-like sori, 

 mixed with a few jointed threads. [Plate 8, C.] 



XII. LITOSIPHON. Frond cartilaginous, filiform, subsolid. 

 Spores scattered, subsolitary. [Plate 8, D.] 



D2 



