530 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



points indicate affinity with Pteris and Cheilanthes. Pterop- 

 sis differs from this in the reticulate veins. In Pleurogramma 

 the sori occupy either side of the costa, running over the inter- 

 stices of the pinnate veins. In Lom,atogramm,a the veins 

 form nearly equal hexagonal arese, and the sorus is one broad 

 continuous marginal patch, approaching in character the dif- 

 fused sori of Acrostichacece. Finally, in Drymoglossum the 

 veins are reticulate, with free veinlets in the meshes, and the 

 sori marginal and continuous, but linear, and sometimes con- 

 fined to the apex. Most of the species of this tribe are tropi- 

 cal or subtropical. One only appears in the Flora of New 

 Zealand. 



7. Grammitace^e, Presl. 



Sori naked, linear, elongated, rarely short, seated on the 

 back of the veins or veinlets. Sporangia shortly pedicellate. 

 Rhizoma for the most part creeping, sometimes subglobose. 



.59 s. The elongation of the sori is not the only character 

 by which these plants are distinguished from Polypodiacece ; 

 but whereas in the latter the sorus is always seated at the tip 

 of a vein or veinlet, it is here as constantly placed on the back. 

 From Tcenitidece they differ in the sori being confined to the 

 veins, and not extending over the interstices. The tribe con- 

 sists of two sections, allied respectively to Gravimitis and 

 He^mionitis. The former has the sori seated on the simple 

 veins, the superior or some secondary veinlet ; in the latter 

 they occur on all the veinlets of the branched veins. 



.599. As regards first the allies of Grarti'mitis, Monogramma 

 has a single sorus at the tip of the costa, which is at length 

 veiled by the contracted frond. This is so like PleurograTwrna 

 as to be easily confounded. In that genus, however, the sori 

 are on each side of the costa, a fact which can only be ascer- 

 tained by careful examination. Grammitis has the sori on 

 the middle or rather towards the tip of the veinlets, and con- 

 sequently obhque, by which character again it is distinguished 

 from Pleurogram7na. In Stenogravima the lower veinlets 

 anastomose ; in Meniscium, of which one South American 

 species is arborescent, they form, when confluent, short 

 curved lines. Synammia differs from Grammitis in the 



