42 ERNST ØSTRUP 



Under A. minut. I include var. eryptocephala (cnfr. Cl. 1. a), which 

 can hardly be kept apart from the typical species. 



Achnanthes tylophora (Reichelt) Cl. Reich. Schöhsee, 199 (Stauron. 

 tyl.), A. S.Atl., Tab. CCXLII, figs. 17—18 (Achn. exigua). 

 Apavatn (S., two samples) A. F. 

 Area: Eur. 



Subgenus Achnanthidium (Ktz. 1844) Heib. 1863. Cl. Syn. II, 191. 



Achnanthes Calcar Cl. Cl. Syn. II, 174. Cl. Fini., Tab. III, fig. 8. 



6 samples S. 2. S.W. 1. X. 2. E. 1). 



Area : Eur. 



Cleve places this species under "Eucocconeis". When I have moved 

 it from there, it is owing to the horseshoe marking, which, it seems to 

 me, approaches it to the group of Achn. lanceolata. 



Achnanthes coarctata (Brés.) Cl. Syn. II, 192. V. H. Tit., Tab. VIII, 

 fig. 327. 



39 samples (S. 9. S.W. 8, N.W.I, X. 6. E. 13. s. 1. 2 . Hot spring: 1. 



Area: Eur., Af., As.. Am., Grl., J. M., B. E., Spb. 



I have given a figure of a square form of A. coarctata on Tab. 

 nost. IV, fig. 61. It resembles somewhat the A. coarct. elineata Lgst., figured 

 in O. M. Pat., Tab. 1, fig. 8, which variant, however, is referred by Cleve, 

 1. c. to the typical species. I found it in a sample from Vik (S.) H. Js. 



«Achnanthes lanceolata Bréb. Cl. Syn. II, 191. V. H. Tit., Tab. VIII, 

 fig. 336. 



140 samples (S. 53, S.W. 29, X.W. 10, X. 10, E. 38 ). Hot springs: 9. 

 Area : Ubiquist. 



Var. capitata O. M. O. M. Pat., 8, Tab. I, figs. 6—7. 



Krökur (S.) H. Js., Skutustaôir (E. two samples: B. B. 

 Area: Am. 



Var. dubia Grün. Cl. Syn. II, 192. V. H. Trt., Tab. VIII, fig. 337. 

 Apavatn (S.) A. F. 

 Area: Eur., Am. 



Var. eltiptica Cl. CI. Syn. 1. c. Cl. Fini., Tab. Ill, figs. 10-11. 

 Apavatn (S. A. F.. Hornafjôrôr (E.) St. 

 Area: Eur. 



Var. fœroensis Øst. Øst. Fær. Fresh w. 277, fig. 44. 



58 samples (S. 22. S.W. 7. X.W. 1. X. 1, E. 17. s. 1. 3). Hot springs: 2. 



Area: Eur., B. E. 



Var. siibinflata var. nov., Tab. nost. IV, fig. 62. 

 Long: 15 ju, lat : 4 ju, str. 14 in 10 fi. 



Valva lineari, in medio paululum inflata, apicibus rotundatis. 

 Striis per totam valvam radiantibus. 



