170 BRITISH DESMllHACK.E. 



margin not tumid, gradually attenuated towards each 

 extremity, near the apices rather suddenly nan-owed 

 into tin obtuse cone; cell-wall delicately striated, from 

 17-24 striae visible across the cell, brown or reddish- 

 brown in colour ; chloroplasts obscurely ridged, with 

 6 or 7 pyrenoids in a central series ; terminal vacuoles 

 with a large number (about 20) of moving granules. 



Zygospore unknown. 



Length 432-528 /x; breadth 35-45 /x. 



ENGLAND. Cumberland ! Westmoreland! (Ralfs). 

 Lancashire! N. Yorks ! Essex! Warwick (Will*). 

 Surrey ! (Rulfs). Sussex (Ihtlfs). Kent (Ralfs). 

 Hants! (Roy). Cornwall! (Rolfs). 



WALES. Capel Curig, Carnarvonshire ! (Cooke 

 Wills). 



SCOTLAND. Widely distributed ! (Roy fy Bix*<'tt). 



IRELAND. Donegal! Mayo! Galway! Kerry! 

 Dublin and Wicklow (Ardtc'i). Antrim ! 



Geor/r. Distribution. France. Germany. Austria 

 and Gralicia. Italy. Norway. S \veden. Denmark. 

 Bornholm. N. Russia. Ceylon. United States. Brazil 



e/ 



(var.). 



The apices of this species are very incorrectly depicted by 

 both Ralfs and Cooke, the apical attenuation being greatly 

 exaggerated. There are also more striations on the cell-wall 

 than are indicated by Ralfs. 



The Desniid which Ralfs and all subsequent authors have 

 referred to "Cl. attenuatum" appears to be somewhat different 

 from the original Cl. attenuation Uhrenb. ; hence Delponte's 

 name " Cl. candianum." Uut since Ehrenberg's species has 

 never been identified with anything else, it would only create 

 confusion to upset the present unanimous interpretation 

 accorded to the name CL attenuatum. 



40. Closterium turgidum Ehrenb. 

 (PI. XXII, figs. 4, 5.) 



Closterium tunji<lnm Ehrenb. Infus. 18.38, p. 95, t. (J, f. vii ; Mencgh. 

 Syiiops. Dcsni. 1S40, p. 2:34; Hass. Brit. Freshw. Altf. 18-45, p. 371, t, 87, 

 t. 3 : Kali's, Brit. Dosin. 1848, p. 165, t, 27, f. 3 ; Airh. in Pritcli. Infus. 

 18(il, p. 747, t. 3, f. 40 ; Kabenh. Flor. Europ. Al-ar. Ill, 1868, p. 12!) ; 

 Kirclm. Alg. Schcs. 1878, p. 138 ; Wolle, Dosni. U.S. 1884, p. 44, t. 6, 



