786 



SYSTEMATIC HISTOEY OF THE INFUSORIA. 



(x. 185.) Frustiiles affixed, often aggre- 

 gated. 



S. falccda (K.) . — ^\^aly es arcuate, linear, 

 with obtuse apices, faint stripe, imdulated 

 Tenter. KSA. p. 43, Paris. 



S. Ulunaris (E.). — Valves linear, 

 curved, biliinate, obtuse, attached, more 

 attenuated at base ; stride obsciu-e. EI. 

 1. 17. f. 5. Freshwater. Europe. Valves 

 bent inwards at the middle, so as to be- 

 come bilunate. 



S. longissima (Sm.).— Valve much elon- 

 gated, slightly and gradually attenuated, 

 with capitate apices ; strise 28 in -001". 

 SBD. i. p. 72, pi. 12. f. 95. Botanic Gar- 

 den, Belfast. Is this distinct from S. 

 biceps ? 



S. UcepsiK.). — Much elongated; valves 

 very slender, gradually attenuated, with 

 capitate apices and distinct transverse 

 strife. IvB. p. m, t. 14. f. 18. Fresh 

 water. Europe. 1-100" to 1-60". Front 

 view linear, with striated margins, some- 

 times dilated at the ends. 



S. alpina (Nag.). — Slender, faintly 

 striated ; front view straight, linear ; 

 valves arcuate, very nan-ow lanceolate, 

 with produced capitate apices. KSA. 

 p. 43. Switzerland. 1-600" to 1-336". 

 S. suharcuata (Nag.).— Small ; front 

 view straight, linear, valves slightl}^ ar- 

 cuate, with produced capitate apices. 

 1-2400" to 1-1200". Switzerland. Like 

 S. alpina, but only half the size. Rab. 



S.JlexHosa (Breb.).— Front view broadly 

 linear; valves linear, cm'ved, sometimes 

 flexuose, wdth capitate apices and very 

 fine transverse stride. = J^unofia Jlexuosa, 

 KSA. p. 6 ; & hicejjs, SBD. i. pi. 11. f. 83. 

 Fresh water. France, England. /3, valves 

 two or three times flexed. Differs from 

 S. biceps in having linear, not tapering 

 valves. 



S. pachyceph ala (K. ) . — Front _ view 

 slender, linear ; valves linear, slio-htly 

 arcuate, with cla^iform apices and indi- 

 stinct striee. = Eunotia pachycephala, 

 KSA. p. 6. Fresh water. Europe. 



S. arcuata (Nag.). — Smooth; front 

 view straight, linear, with truncate ends; 

 valves linear, arcuate, with rounded 

 apices. KSA. p. 890. Switzerland. 



S. f/ibbosa (R.).— Front view linear; 

 valves arcuate, tapering to the slightly 

 constricted recurved apices ; venter con- 

 cave, gibbous at the middle. = Navicula 

 Arcus, EL p. 182 ; CymbeUa Arcus, HBA. 

 p. 429 ; Ceratoneis ^ Arcus, KB. p. 104, 

 t. 6. f. 10 ; Eunotia Arcus, SBD. i. p. 15, 

 pi. 2. f. 15. Fresh water. Europe. The 

 frustules are affixed, as in other species 

 of Synedra. 



S. hamata (S.). — Valves linear or 

 linear-lanceolate, ^v-ith suddenly con- 

 stricted, produced, incurved apices ; striae 

 marginal, 30 in -001". SBD. i. p. 73, pi. 

 30. f. 264. Fresh water. Sussex. 



3 * Valves straight, with a circular, defi- 

 nite central pseudo-nodule. 



S. pidcheUa (Ralfs, Kiitz.). — Frustules 

 in fan-shaped clusters on a compressed- 

 dichotomous stipes ; valves lanceolate, 

 obtuse, with a median umbilicus. KB. 

 p. 68, t. 29. f. 87; SBD. i. p. 70, f. 84.= 

 Ctenophora pulcheUa, Breb., Si/nedra 

 Vertebra, Greg. M J. iii. pi. 4. f. 22. Ponds 

 and slow streams. England and France. 

 Strife 33 in -001", Sm. ( JV 7^) 



S. mimdissima (K.). — Very minute ; 

 front view narrow linear ; valves lanceo- 

 late, rather obtuse; striae 36 in -001". 

 KB. p. 63, t. 3. f. 30; SBD. pi. 11. f. 87. 

 Fresh water. Europe. 



S. gracilis (K.)- — Frustules affixed, 

 scattered ; valves lanceolate, acute, with 

 a median pseudo-nodule. KB. p. 64, 1. 15. 

 f. 8 : SBD. i. p. 70, pi. 11. f. 85. Marine. 

 Europe. Striae obscure, 39 in -001", Sm. 



S. Smithii (R.). — Frustules in'egularly 

 affixed; valves lanceolate, acute, with 

 36 very faint striae in '001." = Synedra 

 acicularis, SBD. i. p. 70, pi. 11. f. 86. 

 Brackish water. England. 



4 * Valves with very long aivn-like beaks 



(Toxarium) ; nodule obsolete. 



S. undidata (Bailey). — Valves slender, 

 lanceolate at the middle, tapering into 

 very long, linear, undidated awns, with 

 clavate apices. SBD. ii. p. 97 ; Greg.DC. 

 p. 59, pi. 6. f. 107. = Toxarium undidatum, 

 Bailey, MO. p. 15, figs. 24, 25. Marine. 

 America and Europe. Front view linear, 

 broader ; valves arcuate or straight, wath 

 24 moniliform striae in -001". 



S. Hennedyana (Greg.). — Frustules as 

 in S. undulata, but the awns not undu- 

 late. GDC. p. 60, pi. 6. f. 108. Marine. 

 Scotland. . 



5 * Frustules affixed, aggregated or scat- 



tered ; pfseudo-nodule obscure or in- 

 definite. 



S. parvula (K.). — Front view linear, 

 truncate ; valves broad lanceolate, acute. 

 KB. p. 64, t. 30. f.32. Fresh water. Ger- 

 many and France. 1-1200". Sometimes 

 free, sometimes attached and densely 

 aggi'egated in a radiant manner. 



S. subtilis (K.). — Slender, radiant; 

 valves narrow linear-lanceolate, very 

 acute. KB. p. 64, 1. 14. f. 2 a. = Navicula 



