or THE NAVICTJLE^. 



913 



S. gramdata (E.). — Bacillar, with 

 turgid middle and obtuse ends; trans- 

 verse striae granulated. = Stauroptera 

 gramdata, EB. 1847, p. 484. Canton. 

 1-480". Allied to Fragdaria ? inesotylu, 

 and to Acknantlies ventricosa. 



5* Valves neither cojistricted, rostrate, 



nor furnisJied ivith a sigmoid median 



line, 



t Valves lanceolate. 



S. Plioenicenteron (Nitzsch., E.). — 

 Large, broadly lanceolate or somewhat 

 rhomboid, gi-adually attenuated into 

 rather obtuse apices; stauros slightly 

 dilated outwards, reaching the margin ; 

 sti'ise fine. EA. pi. 2. 5. f. 1; SD. i. 

 p. 59, pi. 19. f. 186. =Bacillaria Phceni- 

 centeron, Nitzsch ; CymheUa Phoenicen- 

 teron, AD, p. 10; Navicula Phcenicen- 

 t£ro7i, E Inf. Common. Europe, Asia, 

 Airica, America, (ix. 139 ; xn. 17, 18.) 

 1-400" to 1-140". 



^. pteroidea (E.). — Large, broadly or 

 sharply lanceolate, with obtuse apices, 

 and very fine, punctated, transverse 

 striae ; stauros linear, reaching the mar- 

 gin. EA. p. 135; EM. pi. 3. 3. f. 7. 

 America. Akin to S. Baileyi; larger 

 than >S'. Phoenicenteron, E. 



S. Bailey i (E.). — Large, broadly lan- 

 ceolate, tapering gradually to the obtuse 

 apices ; surface with very fine longi- 

 tudinal, undulated lines ; stam*os linear, 

 reaching the margin. EA. p. 134 ; EM. 

 several fignres. America. Akin to 8. 

 Plicenicenteron and S. pteroidea, E. 



S. amphilepta (E.). — Lanceolate, little 

 acuminated, with obtuse apices ; stauros 

 linear; striae none, or indistinct. EA. 

 pi. 1. 2. f. 9-13. America, Africa, 

 feiberia. It is scarcely distinct from S. 

 Plioenicenteron. 



S. gracilis (E.). — Slender-lanceolate, 

 gi-adually attenuated into obtuse apices ; 

 stam-os linear, scarcely reaching the 

 margin; striae indistinct, verv delicate. 

 EA. pL 1. 2. f. 14; SD. i. p. 59, pi. 19. 

 f. 186. America, Europe, Asia, Africa. 

 Smaller and more slender than the pre- 

 ceding species. 



S. apiculata (Grev.). — Oval, obtusely 

 apiculate; stauros linear, abbreviated; 

 striae fine, 34 in -001". Edin. New Phil. 

 Journ., U.S., x. pi. 4. f. 8. Californian 

 guano. Inflated, suddenly contracted at 

 the ends into conic beaks; stauros not 

 reaching more than halfway from the 

 median line to the margin. 



S. lanceolata (K.). — Slender-lanceo- 

 late, tapering into the narrow, subrostrate 



ends ; stam'os linear, reaching the mar- 

 gin ; striae obsolete or indistinct. KB. 

 p. 104, pi. 30. f. 24. Falaise. 1-180" 

 to 1-160". 



S. Atlantica (E.). — Small, lanceolate, 

 with obtuse apices ; front view linear. 

 EB. 1845, p. 155. In pumice from the 

 Isle of Ascension. Akin to S. amphilepta, 

 but more obtuse. 1-1152". 



S. salina (Sm.). — Small, slightly con- 

 tracted at the obtuse apices; stauros 

 linear, nearly reaching the margin ; striae 

 faint, 45 in' -001". SD. i. p. CO, pi. 19. 

 f. 188. Marine. Britain. 



S. minuta (K.). — Smooth, lanceolate, 

 rather obtuse, three times as long as 

 broad. KA. p. 89. Thuringia. 1-1200". 



S. duhia (Greg.). — Minute, smooth, 

 nan'ow -lanceolate, with somewhat trim- 

 cate apices ; stauros linear, nearly reach- 

 ing the margin. MJ. iv. p. 11, pi. 1. 

 f. 37. Scotland. When examined under 

 a high power, the valve exhibits two 

 parallel lines within the margin on each 

 side. 



S. staurophccna (E.). — Lanceolate, 

 smooth, slightly conti-acted at the sub- 

 acute apices ; stauros linear, not reaching 

 the margin. EA. p. 135 ; EM. pi. 2. 3. f. 11. 

 North America. Distinguished from S. 

 Phcenicenteron by its abbreviated stauros. 



S. Gregbrii (Ralfs). — Rhomboid-lan- 

 ceolate, Mdth acute apices ; stauros linear, 

 reaching the margin ; striae fine, nearly 

 parallel, 60 in •OQV'.^Staiironeis am- 

 phioxys, Greg. TM. iv. p. 48, pi. 5. f. 23. 

 Scotland. Highly convex, and even in 

 the best position showing the margin as 

 a broad black line, Greg. 



S. inanis (Perty). — Striated, lanceo- 

 late or elliptic-lanceolate, with very fine 

 transverse striae. Perty, Inf. p. 206, pi. 17. 

 f. 7. Alps. In form nearly agreeing with 

 S. linearis, E., but striated. 



S. lineolata (E.). — Broadly lanceolate, 

 with obtuse apices, and parallel, dotted, 

 longitudinal lines ; stauros linear. EA. 

 p. 135, pi. 2. 1. f. 19. Cayenne. 



S. pumila (K.). — Minute, elliptic-lan- 

 ceolate, with acute apices, and short, 

 marginal, punctated, transverse striae ; 

 stauros reaching the margin. KB. p. 106, 

 pi. 30. f. 43. Marine. Christiania. Front 

 view linear, with rounded angles and 

 truncate ends. 1-1440" to 1-1080'. 



S. Achnanthes (E., K.). — Lanceolate, 

 with obtuse apices ; striae distinct, ob- 

 lique ; stauros linear, reaching the mar- 

 gin. KB. p. 106, t. 29. f. 22. = Stauroptera 

 Achnanthes, EA. p. 135, pi. 3. 3. f. 7; 

 EM. pi. 17. 1. f. 10. Austi-alia, Ame- 

 rica, Falaise. 



3jff 



