470 Bacillariese, Achnanthacese, Achnanthes. 



losque et centralem et termiuales prsebens. Frustula e zona con- 

 nectivali visa arcuato-geniculata, solitaria, geminata vel in fascias 

 conjuncta. 



Phamphora plerumque laminaeformia, singula, una? valva? adpo- 

 sita, nonnumquam in granulos secedentia. 



Sectio I. Valva inferior stauroneilbrinis, costis (inter quas series punctorum 

 plerumque plures conspiciuntur) donatse [Grun. in Grun. et Cleve Arct. 

 Diat. pag. 18]. 



1. Achnanthes longipes Ag. Syst. p. 1, Consp. p. 58, N. 1, Ralfs in i9i8 

 Ann. and Mag. XIII, f. 7 et 8, Khrb. Inf. p. 227, n. 326, t. XX, 



f. 1, Kuetz. Bac. p. 77, t. 20, f. 1, W. Sm. Diat. II, P . 26, t. XXXV, 

 fig. 300, Desmaz. C. F. ed. I, n. 1 160, II, n. 1060, Rabenh. Alg. 

 n. 1346 et 1423, V. H. Syn. p. 129, t. 26, f. 13-16, Rabenh. Fl. 

 Eur. Algar. I, p. 311, Truan Diat. Astur. t. 4, f. 12-14, Achnan- 

 thes Carmichaelii Grev. in Hook. Brit. Flor. II, p. 404, Kuetz. 

 Bacill. p. 77, t. 20, f. II, Conferva stipitafa Engl. Bot. t. 2488, 

 Conferva armiUaris Muell. in Nov. Act. Holm. 1783, t. III, f. 67, 

 Diaioma Vexillum Juerg. Alg. exsicc. VI, n. 6, Achnanthes ma- 

 cropus Kuetz. mscr., Achnanthes hrevipes Kuetz. non Ag. — Ma- 

 xima, ad 200 a. longa; valvis lineari-ellipticis, nonnumquam medio 

 leniter constrictis, utroque fine obtusis, costis validis transversis 

 circ. 6 in 10 a., inter quas strije binse moniliformes tum suboppo- 

 sitse tum alternantes adsunt; valva superiori rhaphe genuina ca- 

 rente, subinde ad apices areola parva hyalina praadita, valva infe- 

 riori rhaphe genuina zona hyalina tenui cincta donata; nodulo 

 centrali in staurum angustum transverse protenso; zona connecti- 

 vali subtiliter transverse striata, striis per plicas longitudinales 

 interruptis. 



Hab. ad algas marinas frequenter, irnprimis ad oras britannicas 

 (Greville, Harvey, Ralfs, W. Smith), Belgii (Van Heurck) in 

 mari baltico (Dannfelt), ad oras Gotlandia? (Cleve), in mari me- 

 diterraneo et adriatico, passim (Kuetzing, De-Toni), in mari cana- 

 riensi (Kuetzing). — Stipes plus minus crassus, elongatus. — Var. 

 COnstricta Grun. in Juhl. — Dannf. Balt. Diat. p. 17. Ad « Oster- 

 gan » Gotlandia 1 (Cleve, Juhltn-Uann.). — forma minor Cleve 

 Diat. West Ind. archip. p. 10. Ad u S. Bartholomew» oceani Indise 

 occidentalis. 



2. Achnanthes costata Grev. Diat. from the Tropics p. 438, t. VI, 1P19 

 f. 8-10, Cleve et Grun. Arct. Diat. pag. 18. — Valvis elongato- 

 lineari-oblongis, 60-75 u. longis, apice ellipticis, delicate costatis, 



