Laing, — On some Species of Delesseria. 449 



larly serrulate, bearing in two oblong patches on either side 

 of the costa numerous irregularly-arranged tetraspores of the 

 usual type. The tetraspores are not confined to the sporo- 

 phylls, but are also found below the apices of the pinnules, 

 where the sporophylls are absent. Cystocarps not seen. 



Hab. St. Clair, Dunedin ; Wycliffe Bay, Otago Peninsula; 

 Mongonui, Chatham Islands ! (Ruapuke Harbour and Stewart 

 Island : Lyall. Lord Auckland Group and Campbell Islands : 

 Sir J. D. Hooker.) 



Delesseria linearis, sp. nov. 



I have had for some time in my possession what is appa- 

 rently a very distinct species of Delesseria, not yet described. 

 I have found it at Lyall's Bay on two occasions only, once 

 growing on a Coralline, and on the second occasion epiphytic 

 on Fterocladia. It is apparently rare. On account of its 

 shape I propose to call it D. linearis. The species is remark- 

 able for the complete disappearance of the costa about one- 

 third of the way up the frond. Agardh, in his description of 

 the genus (" Epicrisis Floridearum," p. 478), states that, "in 

 those species in which the costa is more or less obsolete and 

 evanescent externally, the costal cells are nevertheless rather 

 frequently continued to the tip. In these species the whole 

 longitudinal increase in length of the frond is seen to depend 

 upon the evolution and subdivision of these cells." This is 

 the case with D. crassinervia, in which the costa becomes ex- 

 ternally obsolete a few millimetres from the apex of the frond; 

 but the longitudinal row of cells of which it is formed may be 

 traced to the growing point, where they terminate in a single 

 cell. In D. linearis, however, the costa disappears completely 

 about one-chird of the way from the base of the frond, and 

 there is beyond that point no differentiation of the parenchy- 

 matous cells. However, a terminal cell is readily seen, and 

 below it the cells-are flabellately arranged, evidently as a result 

 of its division. In other i-espects the plant conforms to the 

 normal type of the genus. 



Hab. Lyall's Bay, Cook Strait. 



Description of species : D. linearis, sp. nov. Frond simple, 

 linear sessile, narrowed towards the base, epiphytic, 40mm.- 

 50mm. long, 4mm. -5mm. broad, apex obtuse, margin entire. 

 Costa indistinct, disappearing one-third of the length of the 

 frond from the base, otherwise without veins. Sporophylls 

 arranged in acropetal succession up the centre of the frond, 

 generally singly (but two' or three sometimes spring from one 

 point, and sometimes secondary sporophylls of similar charac- 

 ter arise from the backs of the primary ones), suborbicular, 

 emarginate, and slightly stipitate, 1mm. -2mm. in diameter. 

 Numerous tripartite tetraspores occupy the whole surface of 

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