OLOSTEIJIUM. 1 V :> > 



or golden-brown colour, and is very finely striated. Tlirsr 

 striations arc imt infrequently subspiral in their arrangement, 

 and when examined carefully they arc seen to consist of a 

 series of fine punct:i>. Towards the apices the punctiu are 

 often no longer arranged in lines, but become irregularly 

 scattered. 



The species is distinguished from CJ. fnr</i<linii by its some- 

 what smaller size, its relatively greater length and slighter 

 curvature, and by its much narrower, truncate apices. The 

 cell-wall is also rather more finely striated and the stria? 

 consist of punctae. 



Liitkemiiller has found specimens of this species with a 

 length of 720 /j, and a Brazilian form (f. maxima Nordst.) 

 reaches a length of 680 // and a breadth of 65 /u. 



Cl.Pritchardinnumvar. minus West (Alg. W. Ireland, 1802, 

 p. 121, t. 19, f. 13) does not belong to Cl. Pritchardianum. 

 We have only seen one specimen of it, and until we obtain 

 further information with regard to it, it must be left in 

 abeyance as a form to be inquired into. 



48. Closterium pronum Breb. 

 (PL XXIII, figs. 1-3.) 



Closterium pronum Breb. Liste Desm. 1856, p. 157, t. 2, f. 42 ; Arch, in 

 Pritch. Infus. 1861, p. 750; Rabenh. Flor. Europ. Algar. Ill, 1SOS, p. 

 130 ; Lmnd. Dosm. Suec. 1871, p. 81 ; De Toni, Syll. Alg. 1889, p. 852 ; 

 West, Alg. W. Ireland, 1892, p. 125 ; Roy & Biss. Scott. Desm. 1894, 

 p. 247 ; Nordst. Index Desm. 1896, p. 200 ; West & G. S. West, Alg. S. 

 England, 1897, p. 482 ; G. S. West, Alga-fl. Cambr. 1899, p. 113 ; West 

 & G. S. West, Alga-fl. Yorks. 1900, p. 50 ; Alg. N. Ireland, 1902, p. 25 ; 

 Scott. Freshw. Plankton, I, 1903, p. 525. 



Cl. Lima Ltind. Desm. Suec. 1871, p. 82. 



Cl. pronum a. typicum Klebs, Desm. Ostpreuss. 1879, p. 19, t. 2, f. 12 a. 



Arthrodia prona Kuntze, Revis. gen. plant. 1891, p. 884. 



Cells narrow and very elongated, 40-50 times longer 

 than their diameter, straight or very slightly curved, 

 outer margin not more than 10 15 of arc, very gradu- 

 ally attenuated to the apices, which are long and pointed 

 although the extreme end of the cell is rounded ; cell- 



O 



wall smooth and colourless [but, according to Brebisson, 

 yellow-brown and finely striated] ; chloroplasts 

 obscurely ridged, with a row of 8 to 10 pyrenoids ; 

 terminal vacuoles some distance removed from the 

 apices and occupying all the apical parts of the cell, 

 containing from two to six moving granules. 



