12 



P. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



35. 

 36. 

 37. 

 38. 



39. 



40. 

 41. 

 42. 

 43. 

 44. 

 45. 

 46. 

 47. 

 48. 

 49. 

 50. 

 51. 

 52. 

 53. 

 54. 

 55. 

 56. 

 57. 

 58. 

 59. 



(;o. 



61. 

 62. 

 63. 



Central area small or indistinot N- miiltiseriata Ghon. 



— — orbicular — N. maculosa Donk. 



Size small. L. 0,015 to 0,04 mm 37. 



— large. L. 0,05 mm. and more 43. 



Stri» 14 in 0,oi mm 38. 



— 6 to 10 mm 40. 



Median strise stronger N. cincta Ehb. 



— — not 39. 



Ends obtuse N. BecJcii Pant. 



— acute N. ammophila Grtjn. 



— subcapitate N- cryptocephala Kiiiz. 



Strise coarsely lineate 41. 



— apparently smooth 42. 



Valve rhomboidal N. Raphoneis Grun. 



— elliptio-lanceolate N. Formenterce Cl. 



Terminal strise strongly marked N. Imngarica Grun. 



— — not — — ■ N. costulata Gbun. 



Ends protracted 52. 



— not — 44. 



Central area distinot 46. 



— — not — 45. 



Marine habitat N- spuria Cl. 



Fresh water — N. radiosa KtJTz. 



Strise coarsely lineate 47. 



— finely — 49. 



Marine habitat 48. 



Fresh water — N. vulpina Kutz. 



Valve narrow lanoeolate, not very convex N. pinnata Pant. 



— broadly — convex N. fortis Greg. 



Valve not very convex N- avenacea Bbéb. 



— convex, with conical ends 50. 



Ends very elevated and compressed N. compressicauda A. S. 



— not — — — 51. 



Central area small N. cancellata Donk. 



— — large N. Centrastcr Cl. 



Ends subrostrate, obtuse JV. viridula Kutz. 



— non-rostrate 53. 



Ends subcapitate N. rJiynchocephala Kutz. 



— acute N. gotlandica Grun. 



Frnstule arcuate 55. 



— non — 56. 



Striae about 18 in 0,oi mm iV. gcnujlexa Kutz. 



— — 10 — — iV. Bollcana Grun. 



Strise crossed by lateral areas or blank bands 57. 



— not — — — — — 64. 



.StrijE crossed by a single, narrow area 58. 



— — — several longitudinal bands 60. 



Apiculate iV. Galea Brun. 



Non-apicnlate 59. 



Axial part of the valve elevated N. superimposita A. S. 



— — — — not — N. Fhi Ch. 



Blank lines straight N- arata Grun. 



— - undulating 61. 



Axial area unilateral 62. 



— areas bilateral 63. 



Valve slightly convex N. imperfecta Cr,. 



— very — N. monodon Grun. 



Valve sliglitly convex iV. consors A. S. 



— very — N. guttata Grun. 



