222 BRITISH DESMIDIACK^;. 



3. Tetmemorus laevis (Kiitz.) Ralfs. 

 (PI. XXXII, figs. 11-1G.) 



Closterium /,rrr Kiitz. Phycolo^. n'orin. 1S4.">, p. 132. 



Tetmemorus Isevis (Kiitz.) Ealfs, Brit. Desm. lS48,p. 140, t. 24, f. 3; Avcli. 

 ^H in Pviteh. Tnfus. ]801,p. 740; L'abenh. Flor. Europ. Algar. Ill, ]SOS, 



p. M.(>; Kirehn. Al^. Sohles. 1878, p. 145; Wolle, Desm. U.S. lss|, 



p. !)1, t. 20, f. 3 ; t. 50, f. 35 ; Cooke, Brit. Desm. 1SSO, p. 49. 1 . I'.i, f. 2 ; 



ll.-uis--. rro.lv. Ali^onn. liohin. isss, p. 188 ; Do Toni, Syll. Al--. iss'.i. 



p. 808 ; West, Alor. W. Ireland, 1S'.)2, p. 132; Eoy & Biss'. Scott'. D.-sm. 



IS'.M.. p. 212; Nor.lst. Index Desm. 1S{)0. p. 15:i ; West .V G. S. W.-l 



Al-. S. Eno-land, 1897, p. 483; Alo-a-fl. Yorks. 1900, p. 00; Alg. N. 



Ireland, 1902, p. 27. 

 Paiium (Tetmemorus) l.vve Gay, Mono^r. loc. Conj. 1884, p. 71. 



Cells small, 3-J-4J (commonly 4) times longer than 

 their diameter, with a slight median constriction ; 

 semicells very gradually attenuated to the apices ; 

 apex fairly broad and rounded, with a deep median 

 incision; cell- wall minutely punctate; chloroplasts 

 Avitli a median series of 3-5 pyrenoids ; semicells in 

 side view more attenuated than in front view, especially 

 near the apex. 



Zygospore ovoid, compressed, enclosed within an 

 outer, compressed, quadrate coat. 



Length 67-5-123 /A; breadth 20-3 1 '5 /ot; breadth of 

 isthmus 16-27 /A; length of zygosp. 57 /x. 



ENGLAND. Cumberland! Westmoreland ! (7//'x.sv//). 

 W., N., and E. Yorks ! Lancashire! Leicester (Roy). 

 Essex! Norfolk (CW>/,v>). Warwick ( Wills) . Surrey! 

 Sussex (Rfilfs). Hants! (Hrnm-ft). Kent! Devon! 

 Cornwall (Marquand) . 



WALKS. General and abundant ! ; at 2,200 ft. on 

 Glyder Fach, Carnarvonshire. 



SCOTLAND. General! Zygosp. from Whitestripes 

 Moss and Aboyne, Aberdeen; Cammie in Strachan, 

 Kincardine (7?o// $ 7//.v.sv//). At 3,500 ft. on Loch- 

 iifigar ! Outer Hebrides ! Orkneys ! Shetlands ! 



1. 1. 1 1<; LAND. General, but not common ! 



(irni/r. Distribution. France. Belgium. Germany. 

 Austria and Galicia. Italy. Norway. Sweden. Den- 

 mark. Horn holm. N. and S. Russia. Nova Zembla. 

 Greenland. Singapore. Australia. New Zealand. 



