74 BRITISH DIATOMACEiE. 



Sect. IV. Pseudo-nodule obsolete ; frustule straight. 



21. Sjmedra crystallina, Kiltz. V. much elongated, slightly in- 

 flated at the centre and extremities; striee reaching across the 

 valve, 26 in -OOl". Length -0180" to -0266". v.v. 



Kiitz. Bacill. xvi. 1. Diatoma crystnllinum, Ag. Consp. p. 52. et Grev. B. F. 

 p. 407. ad specim. authen. quse communicavit cl. Dr. Greville. 



Marine. Poole Bay, Sept. 1851, W. Sm. 

 Plate XII. 101. 



22. S3niedra superba, Kutz. V. linear, slightly attenuated from 

 the centre towards the rounded extremities ; strice very distinct, 

 27 in •001", reaching across the valve ; pedicel somewhat elongated. 

 Length of frustule -0098" to -0208". v.v. 



Kiitz. Bacill. xv. 13. 



Marine. Poole Bay, Nov. 1849, W. Sm. 

 Plate XII. 102. 



23. SynedraGallionii, ^7ir. V. attenuate, extremities obtuse ; striag 

 not reaching across the valve, .36 in "OOl"; pedicel not elongated. 

 Length of frustule -0060" to -0112". v.v. 



/3. A shorter and stouter form. 

 Ehr. Inf. xvii. 2. Kiitz. Bacill. xxx. 42. 



Marine. Isle of Man, Mr. Johnson. /3. Beachy Head, Aug. 1852, W. Sm. 

 Supp. Plate XXX. 265. Var. /3. Supp. PI. XXX. 265/3. 



24. Sjrnedra fulgens, W. Sm. V. slightly inflated at the centre and 

 at the rounded extremities ; striae reaching across the valve, 36 in 

 •001"; frustules arranged in a flabellate manner upon a branched 

 pedicel. Length -0068" to -0164". v.v. 



Exilaria fulgens, Grev. S. C. F. pi. 291. Licmophora fulgens, Kiitz. Bacill. 

 xiii. 5. ad spec, autlien. quse niisit amicus De Brebisson, Jan. 1853. 

 Prit. Anim. xvi. 20. 



Marine. Poole Bay, Sept. 1851 ; Jersey, Aug. 1852, W. Sm. 



Plate XII. 103. 



There is nothing in the structure of the frustule to warrant the separation 

 of this species from the present genus. 



