188 P. T. CLEVK, SYNOPSIS OF THE NAVICULOID DIATOMS. 



Ärtificial Tcey. 



^ , Valve biconstricted Ä. trinodis Akn. 



not constricted 2. 



„ , Lower valve with a transverse fascia 3. 



' \ — — witliout 4. 



I Valve narrow, linear-lanceolate A. affinis Grun. 



3. •! — naiTosv, elliptical A. hungarica Geun. 



I — elliptical, rostrate A. exigua Geun. 



4 



( Valve broad and sliort 5. 



\ — narrow aud elongated . . . > 7. 



j. J Striae fine (25 in 0,0 1 ram.) A. Biasolettiana KiJTZ. 



" ' \ — coar.se (10 to 14 in O.oi mm.) 6. 



J Valve broadly lanceolate A. delicatula KijTZ. 



I — elliptical A. Hauckiana Grun. 



„ I Strise 12 to 16 in 0,01 mm 8. 



21 or more '. • 1.1. 



Valve lanceolate A. Hudsonis Geun. 



inear A. glabrata Gbun. 



Striffl 21 in 0,01 mm A. exilis KfJTZ. 



— 24 or more in 0,0 1 mm 10. 



^, I Valve with parallel margins 11. 



' \ — — slightly convex 12. 



Frcsh water habitat A. linearis "W. Sm. 



Marine A. tceniata Grun. 



^j, J Entls subcapitato A. microcephala K.utz. 



\ — obtuse A. miniitissima Kutz. 



8. { ^^^ 



11. P' 



1. A. miniitissima Kutz. (1833). — Linear with somewhat attennate and obtuse encls. 

 L. 0,015 to 0,02; B. 0,003 to 0,004 mm. Upper V. with narrow, linear axial area. StrifE abont 

 26 in 0,01 mm. parallel. Lower V. without axial area and with small, transverse central area. 

 StrifE about 25 in 0, 01 mm., stronger in the middle, slightly radiate. — Dec. N:o 75 (1833) accor- 

 ding to Lägst. Grun. A. D. p. 23. V. H. Syn. p. 131 Pl. XXVII f. 35 to 38. A. exilis W. Sm. 

 B. D, II Pl. XXXVII f. 303. 



Fresh water: Sweden! Germany! England! Belgium (V. H.), probably common everywhere. 

 Var. cryptocephala Grdn. — Smaller, with slightly capitate ends. L. 0,oi2 to0,oi8; B. 0,oo2 

 to 0,003 mm. Strite abont 30 in 0,oi mm. — V. H. Syn. Pl. XXVII f. 41 to 44. 

 Fresh water: Finland! 



2. A. microcephala Kutz. (1844). — Linear lanceolate, with snbcapitate ends. L. 0,009 

 to 0,026; B. 0,003 mm. Upper valve with linear axial area and parallel strifc, 30 — 3(i in 0, 01 mm., 

 the median strite abbreviated. Lower V. without axial area and with small transverse central 

 area. Strise about 32 in 0,oi mm. slightly radiate. — A. microcephalum Kutz. Bac. 75 Pl. III 

 f. 13, 19 (1844). Grun. A. D. p. 22. V. H. Syn. p. 131 Pl. XXVII f. 20 to 23. Navicala 

 puchijcepiiala Schum. Preuss. D. 2:te N. II f. 44? 



Fresh water: Sweden (Helsingland)! Belgium (V. H.). 



Achnanthidium microcephalum W. Sm. B. D. is probably Anomoeoneis exilis Grun. 



3. A. lim\ar!s W. Sm. (1855). — Linear with rounded ends. L. 0,oi to 0,02; B. 0,oo3 to 

 0,004 mm. Upper V. witli narrow, linear axial area and parallel stria>, 24 to 27 in 0, 01 mm. 

 Lower V. without axial area and with small and transverse central area. Strict 22 to 28 in O, o 1 

 mm. — Achnanthidium Un. W. Sm. Ann. and Mag. Nat. Hist. 1855 p. 8 Pl. I f. D. .B. D. II 

 p. 31 Pl. LXI f. 381. Achnanthes lin. Grun. A. D. p. 23. V. H. Syn. p. 131 Pl. XXVII f. 31, 32. 



Frcsh water: Norway (Dovre)! England! Belgium (V. H.). 



