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Frustulia viridis Kützing, Linnæa,. 1833, p. 551. Navinda
viridis Ehr., Die Infus. p. 182. t xiii. f. 16. t. xxi.
fi<T. 12. Frustulia viridis Jenner, in El. of Tunbridge
Wells, p. 203. Nav. biceps ? Bory, Encyc. Métb. 11824.
llah. Frequent in Sussex : Air. Jenner. Cheshunt ;
A. II. II. Aberdeen ; Dr. Dichie. Ireland : Air. Aloore.
This is one of the finest and most beautiful of all the
Diatomaceoe. In young specimens the frustules arc not at all
or scarcely infiated in the centre.
86. S U E IR E L L A Turp.
Char. Frnstules large, solitary, quadrangular; angles produced,
striated.
Derivation. Named in honour of Dr. Suriray.
This seems to he a well-marked genus. To it should be
referred, in addition to the two siiccies described below,
Navicula? splendida, N. ? undulata, N. ? constricta, which would
stand thus : Surirella splendida, S. constricta, and S. undxdata.
The two latter species differ from all the others m the transverse
striæ being in single and not double scries, tha t is, they
pass entirely across the frustule. This genus seems to have
been indicated by Fhrcnbcrg.
1. SuilIKEELA BISERIATA Brch.
Plate C II. Fig. 1.
Char. Frnstules in front view quadrangular, about three
times as long as hroad, with straight sides and tx'uncate extremities
; in lateral aspect oval, with pointed ends.
Navicida? hifrons Flir., Die Infus. p. 186. t. xiv. fig. 2.
Surirella hiseriata Jenner, in F l. of Tunbridge Wells.
llah. Ashdown Forest, Piltdown Common, Broadwater
Forest, and Warbleton : Air. Jenner.
2. S u r ir e l l a J e n n e r i Ilass.
Plate CII. Fig. 15.
Char. Frustules in front view ohtuse at each extremity, and
with striæ in double sex'ies ; end view quadrangular, each
angle heing prolonged into a thin plate.
Surirella hifrons Jenner, loc. cit. p. 204.
Ilab. Warbleton : ilfr. Jenner.
A very distinct and beautiful production, having no relation
with tlie N. hifrons of Fhrcnberg.
87. ENCYONFMA Kütz.
Char. Frustules cymbiform, enclosed within a membrane.
Derivation. From sgKVos, fu ll, and vyga, a thread.
1. F n c y o n e î ia b r o s t r a t um Kütz.
Plate C. Fig. 10.
Char. Frustules striated, straight, gibbous, small, enclosed
within a transparent membranous tube.
Encyonema prostratum Kütz., Die Krcselschaligcn, &c.
p. 82. t. 25. f. 7. Encyonema paradoxum Kütz., Synops.
Diatom. Alonema prostratum Berk., Glean, of Br.
Algæ. Schizonema ? prostratum Grev., in Hook. Br. FL,
p. 414. ; Ilarv. in Manual, p. 214. Fncgonema prostratum
Jenner, in Fl. of Tunbridge Wells, p. 206.
llah. On the boards of a sluice forming a thin, brown
mucous stratum : Rev. J. M. Berkeley. On the hoards
of a sluice on Cheshunt Marshes : A. II. II. Bramblc-
tyc, near Forest Eow, and in the stream which parts
Sussex and Kent, between Bodiam and Sandhurst.
i\ very singular and beautiful production, coming near to
Schizonema.
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