Acta Societatis pro Fauna et Flora Fennica, 47, N:o 4. 53 



* 





* 



var. xanthidioides, nova var. Cellulae ut in forma 

 typica, fortasse paullo magis rotundato-ellipticae; polis 

 semicellularum spinis singulis, ut in forma typica, graciliter 

 curvatis instructis; membrana semicellularum (a f route vis.) 

 in area centrali incrassata fuscescentique, ut in speciebus 

 generis Xanthidii. Long. 57 ,a, lat. sine spin. 46, lat c. sp. 

 68, long. spin. circ. 15 /t. (N:o 445 a). — Quae var., ut etiam 

 var. incrassatus Gutw. Flor. alg. Lwowa t. 3 f. 5 et West, 

 North. Amer. t. 16 f. 4, pag. 254), A. incrassatus Lagerh. 

 Amer. Desm. t. 27 f. 18, etc., formae transeuntes sunt inter 

 genera Xanthidium et Arthrodesmum. Forma nostra, nisi area 

 centrali, non & forma typica differt, qua re ad hanc speciem 

 pertinet. Quod formae eius generis in genus Arthrodesmum 

 inclusae sunt, mihi videtur diagnosis huius generis corrigen- 

 da esse eo animo, ut etiam formas et species in area cen- 

 trali semicellularum incrassatas includet: [Cfr. West, Mngr. 

 IV pag. 88] - — - — ; centre of semicell quite plane and 

 undifferentiated or sometimes with a thickened (smooth or 

 scrobiculated) more or less prominent central area; vertical 

 view elliptic, with no median protuberans, but sometime with 



a median thickening. 



In Desm. Millstatt. pag. 70 Lotkemoller formam 

 commemoravit, quae fortasse synonyma varietatis nostrae 

 habenda sit. „Die Zellhaut", inquit, „im Mittelfelde deutlich 

 verdickt und daselbst haufig gelblich gefarbt. Scheitel con- 

 vex, nicht wie bei var. incrassatus Gutw." 



Tab. 4 fig. 34—35. 



var xanthidioides nob. forma depressa, nova f. Differt 

 semicellulis magis depressis; spinis magis convergentibus; 

 area centrali incrassata multo minore minusque colorata. 

 Long. 38 [a, lat. sine spin. 42^, lat. c. sp. 68, long. spin. 15, 

 isthm. 1 1 fi. (N:o 445 b). — Fortasse hae quoque formae 

 hue adnumerandae sint: Delponte, Spec. Desm. subalp. 

 *• 14 f. 13, 15, 17, 20—21; Ehrenberg, Infus. t. 10 f. 18; 

 Rabenhorst, Bacill. Sachs, fasc. 6. N:o 51 et t. 6; Ralfs, 

 Brit. Desm. t. 20 f. 3 d (synon. = f. attenuata Jacobsen, Desm. 

 Danem. pag. 203). 



