Acta Societatis pro Fauna et Flora Fennica, 49, N:o 7. 47 



spin. long. 80—86, Iat. 64—76, crass. 53, isthm. 25 (i). [N:o 

 738 b, c.]. 



To this variety belong probably also: 



X. antil. v. laeve f. irregularis West, New. Brit. Alg. (1894) pi. 2 

 f. 44; West, Monogr. IV (1912) pi. 109 f. 4. — var. fasciculoides f. 

 inevoluta L u t k e m., Attersee (1893) p. 548 [consult West, Mngr. IV 

 page 88!]. — (?) X. antilop. Levander in Festschr. f. Palmen (1905) 

 pi. 1 f. 9; (?) Lobik, Desm. Pskow (1913) pag. 82 fig. 10 (the right); 

 (?) Kufferath, Flor. Alg. Luxembg. (1914) page 300 f. xyl. 10—11. 



I have seen monstrous semicells of this variety with a 

 little accessory spine at each apical angle. Such an ab- 

 normal cell is probably also X. fasciculatum, Hirn, Desm. 

 Finnl. (1903) pi. 2 f. 35. 



Mab. Keuru (C); near Tammerfors (W). — PI. 4 fig. 

 19—20. 



h) var. oligacanthum S dim idle, Chlor. Virnheim(i894) 



pi. 7 f. 10; West, Mngr. IV (1912) pi. 109 f. 5. 



The typical form has a not differentiated central area 

 (as var. laeve). But the Finnish forms always have a thick- 

 ened (smooth or scrobiculate) central area. 



Here belong the following forms: 



var. oligacanth. forma West, Frw. alg. N.-Irel. (1902) p. 31; 

 West, Mngr. IV (1912) pi. 109 f. 6. 



Mab. Messuby (W). — PI. 4 fig. 21—22. 



i) var. hebridarum West, Furth. contr. Scott. Pi. (1905) pi. 



7 f. 21; West, Mngr. IV (1912) pi. 109 f. 7 and pi. 110 f. 1—2; Strom, 

 Phytoplankt Norweg. (1921) pi. 1 f. 16 page 30. 



The apical spines single or two. 



Hab. Keuru (C); „Isthmus karelicus" (SE). PI. 4 



fig. 23—24. 



k) var. Crameri, nov. nom.; X fasciculatum Cramer in 

 Hedwigia 1863 pi. 12 f. 2. 



Anguli superiores spinis geminatis parallele suprapositis 

 ornati, anguli basales spinis binis non suprapositis sed iuxta 

 defixis divergentibusque (ut fiat angulus circ. 90° inter eas). 

 Semicellulae plus depressae. Membrana in centro semicir- 

 culo vel 3 / 4 -circulo scrobicularum ornata praetereaque in- 

 crassata luteola. A vertice visum plus rhomboidiforme. Cum 



