312 Transactions. — Botany. 



Length of frond, J^ inch; breadth, front view, -g-^o inch; side view, 

 ■ffooo mch. 



Eare : from an almost dry ditch near the Fendalton road. 



This pretty httle plant is evidently closely allied to forms described from 

 America, Bengal, and Hong Kong. From the first-named country, 

 Prof. Bailey describes T. verticillatum and T. gracile ; from Bengal we have 

 Docidiiwi (Triploceras) jyristidcB, Hobson, and also T. gracile, Archer, from 

 Hong Kong. But in none of these can I find the two tridentate terminal 

 processes, and the three tri-cuspidate processes at their base, of my 

 T, tridentatum. The American species, as shown in Kalfs' tab. XXXV., 

 end in simple uni-dentate or bi-dentate processes ; so does the Chinese plant 

 figured by Mr. Archer (Quart. Micros. Journal, 1865, PI. VH.) ; and Mr. 

 Hobson's figure and description (Quart. Journal, 1863, p. 169) leave very 

 much to be desired. Also the number of teeth in each whorl described in 

 all these plants seems to be less than in T. tridentatum, but I lay no stress 

 on this point. 



I can scarcely set down as a mere " variety " a plant showing such 

 considerable differences as these. Unless all previous figures are greatly 

 inaccurate, the terminal and sub-terminal processes of T. tridentatum are 

 sufficiently distinct to render it, I should say, a new species. 

 13. Closterium, Nitzch. 



C. lunula, Miiller. (E. XXVII.) 



Common. 



C. ace7'osum, Schrank. (E. XXVII.) 



Figure 33. 



Common ; also, from Leithfield, plentifully. 



This species seems to vary a good deal in length : some specimens from 

 Leithfield are -g^ inch long : some from Christchurch -^ inch. It is dis- 

 tinguished from C. lunula by greater slenderness and curvature, and by 

 having its vesicles in a single row. Ealfs states that the empty frond is 

 colourless ; many of the species here have a distinct brown tinge. I observed 

 also a tendency in several plants to assume a somewhat sigmoidal shape, 

 the two ends turning opposite ways. 



C. Uneatum, Ehrenberg. (E. XXX.) 



Not common. 



C. selencsiini, sp. no v. 



Figures 15-16. 



Frond bright green, large, stout, visible to the naked eye, distinctly 

 lunate, the outer margin forming a bold circular curve, the inner margin 

 also curved but more slightly ; no inflation at the middle ; ends rapidly 

 tapering, sub-acute, a little rounded, and at the extreme tip turned very 



