Acta Societatis pro Fauna et Flora Fennica, 49, N:o 7. 51 



medio incrassatione prominenti, spinis asymmetrice utrimque 

 prope planum medianum J defixis. Membrana subtiliter 

 porosa. Massa chlorophyllacea e laminis 4 in utraque 

 semicellula, unusquisque singulis nucleis amylaceis, com- 

 posita. Cum spin. long. 76—87—87, lat. 78—87—101; sine 

 spin. long. 61— X— 64,: lat. 55— X— 57, crass. 38, isthm. 

 15—15—19, long, spinae max. 11,5— X— 19 //. [N:o 790 b], 



This new species I formerly regarded as only a variety 

 of X. antilopaeum. But the differences were too apparent. 

 It could not be united with any variety already described 

 although it is nearest to var. hebridarum West, nor could 

 it be made a new variety. It differs from var. hebridarum 

 by the (in front view) elliptical, not sexangulate semicells, 

 the curvate and constantly unpaired, asymmetrically arranged 

 spines, the entirely smooth, slightly protuberant and strongly 

 coloured central area and the, in vertical view, rhomboid- 

 shaped cells. Our species should also be compared with 

 var. oligacanthum S c h m i d 1 e; X. bengalicum Turn., E.-Ind. 

 pi. 12 f. 32 (and Cushman in Rhodora N:o 7, 1905 pi. 14 

 f. 10, which is not identical with Turner's species); 

 X. hastiferum f. inevolutum Nordst., N-Zeal: pi. 4 f. 24; 

 X. hastiferum v. johnsonii West (synon. = X. antilop. f. 

 javanicum Johnson, Rare Desm. II pi. 239 f. 10; (— not 

 Nordstedt 1880!) especially the one semicell with unpaired, 

 asymmetrical spines at the apical angles. 



Mab. Keuru (C); Gov. of Archangel. — PI. 4 fig. 32—33. 



X. tetracentrotum W o 1 1 e f. protuberans West, Mngr. 

 IV pi. 107 f. 3. The Finnish form agrees quite well with 

 the English one, but I think it is very doubtful, whether 

 it is a form of X. tetracentrotum, or would better be placed 

 elsewhere. Compare also X. antilop. v. dimazum Ndt; 

 X. pseudobengalicum nob; X. subhastiferum v. murraui West. 

 — Cum spin. long. 49, lat. 84, sine. spin. long. 49, lat. 46, 

 crass. 27, isthm. 11, long, spinae 19 fi. [N:o 901]. 



Mab. Lempaala (W). — PI. 4 fig. 34—35.' 



X. fasciculatum Ehr.; West, Mngr. IV pi. Ill f. 6—8 

 (Syn. = X. fascic. var. ornatum Nordst., Desm. Gronl. 



