DesmidiecB.~\ iNFrsoRTAL AXTMALcrLES. 263 



end view tliree-lobed, each lobe terminated by a short miicro. Larger 

 than S. dejectum. Length 1 -502nd. 



f f Frond rough, with minute granules. 



STArrRASTKinu lunatum. — Granides puncta-likc, segments externally 

 lunate, -srith an awn at each angle ; end view with thi'ce inflated awned 

 lobes. Its rough frond distinguishes it from all the preceding species, 

 and the inflated awned lobes of its end view from the following ones. 

 Length 1 -856th. 



(B.) — Frond smooth ; angles in end view hroadhj roxmded. 



S. muticum. — Segments elliptic, end view shewing slightly concave 

 sides, and 3 to 5 rounded angles. It possesses a mucous covermg, 

 frequently indistinct. It differs from S. orhiculare by its elliptic 

 segments and numerous coverings. Length 1-6 74th. 



S. orhiculare = Desmtdium orhiculare, (Ehr.) — Segments semi-orbi- 

 cular ; end view bluntly triangular. Sporangia orbicular, with 

 subulate spines. Length 1-1 037th. 



S. tumidum. — Segments smooth, elliptic, or sub-orbicular ; end 

 A'iew bluntly triangular, each angle terminated by a nipple-like pro- 

 jection. Frond large, visible to the naked eye ; with a distinct 

 gelatinous covering. In both views the margin appears striated. 

 Empty fr'ond minutely punctate. Length 1 -200th. 



(C.) — Frond with simple spines, hairs, or (rarely) acute granules ; 

 angles in end view hroadhj rounded and entire. 



S. muricatum = Besmidium apiculosum, (Ehr.) — Segments semi- 

 orbicular, rough with conic granules ; end view triangular, with 

 convex sides and broadly rounded angles. It is larger than S. 

 hirsutum, and not hii'sute ; in the end view also, its sides are more 

 convex. Length 1 -409th. 



S. hirsutum=Xanthidimn hirsutum, (Ehi".) — Semi-orbicular, rough, 

 with numerous scattered hair-like spines ; end view with three 

 rounded angles, and straight or slightly convex sides. Sporangia 

 orbicular, spines short, and branched at the apex. Length 1 -676th 

 to 1 -468th. (P. 12, f. 512.) 



S. teliferum. — Segments reniform, bristly ; end view ti'iangular 

 with concave sides, and broadly rounded bristly angles; spines 

 scattered. It differs from S. hirsutum in its longer spines, which 

 are also fewer, stouter, and in the end view confined to the angles. 



