DIATOMACE^E. 



[ 257 ] 



DIATOMACEJE. 



lines, ends oblique or conical, and with 

 one or more terminal bristles ; marine 

 (PI. 50. fig. 46). 



Corinna. Fr. united into semicircular 

 bands; angles produced, spiniferous, 

 intermediate portion hemispherical, 

 septate; valves ellipsoid, transversely 

 bicostate, apiculate at each end. 



\_Hemiaulus. Fr. single, compressed, rec- 

 tangular, angles produced into tubular 

 direct processes, those on one valve 

 longer than those on the other ; fossil 

 (PL 25. fig. 3). 



Syringidium. Fr. single, terete, acu- 

 minate at one end, two-horned at the 

 other j marine (PI. 18. figs. 32, 33). 



Periptera. Fr. single, compressed ; v. 

 unequal, one simply turgid, the other 

 with marginal wings or spines ; fossil 

 (PI. 18. figs. 66, 67). 



Didadia. Fr. single ; v. unequal, one tur- 

 gid and simple, the other two-horned ; 

 fossil (PI. 18. figs. 61-65). 



Trinacria. Porpeia. Hydrosera (PI. 51. 

 fig. 40). Solium. Zygoceros. Gly- 

 phodiscus. Attheya (PI. 51. fig. 39).] 

 Coh. 18. ANGULAT.E. Valves angular. 



Triceratium. Fr. free ; v. triangular, each 

 angle with a minute tooth or horn ; 

 marine (PI. 17. fig. 29). 



[Syndendrium. Fr. single, subquadran- 

 gular; v. unequal, strictly turgid, one 

 smooth, the other with numerous me- 

 dian spines or little horns branched at 

 the ends (PI. 18. fig. 59).] 



Rabenhorst makes the Angulatse a sub- 

 family of Biddulphieae ; comprising the 

 European genera Triceratium, Trinacria, 

 and Lithodesmium. 



** Frustules enveloped in a mass of gelatine, 

 or contained in gelatinous tubes, forming 

 a frond, 



Mastogloia. Frond mammillate ; frus- 

 tules like Navicula, but hoops with 

 loculi ; freshwater and marine (PI. 51. 

 fig. 26). 



Dickieia. Frond leaf-like ; frustules like 

 Navicula or Stauroneis', marine (PI. 19. 

 fig. 16). 



Berkeleya. Frond rounded at base, fila- 

 mentous at circumference ; frustules 

 navicular; marine (PI. 19. fig. 8). 



Homceocladia. Frond sparingly divided, 

 filiform ; frustules like Nitzschia, ma- 

 rine (PI. 19. fig. 15). 



Rhaphidoglcea. Frustules those of Am- 



phipleura, tufted in radiating gelatinous 

 filaments (PL 19. fig. 11). 

 Colletonema. Frond filamentous, fila- 

 ments not branched ; fr. like Navicula 

 or Pleurosigma ; freshwater. 

 Schizonema. Frond filamentous, branched; 

 fr. like Navicula ; marine (P1.19. fig. 12). 

 Encyonema. Frond filamentous, but little 

 branched ; fr. like Cymbella ; fresh- 

 water (PL 19. fig. 10). 

 Syncyclia. Fr. those of Cymbella, united 

 in circular bands, immersed in an 

 amorphous gelatinous frond ; marine 

 (PL 19. fig. 14). 



Frustulia. Fr. those of Navicula, irregu- 

 larly scattered through an amorphous 

 gelatinous mass; freshwater (PL 19. 

 % 17). 



Micromega. Fr. those of Navicula, ar- 

 ranged in rows, in gelatinous tubes, 

 or surrounded by fibres, these being 

 enclosed in a filiform branched frond ; 

 marine (PL 17. fig. 8). 

 Many other species are noticed and 

 figured in this work under the genera, 

 which have not been described with suffi- 

 cient brevity to allow of their being tabu- 

 lated, or are not well established. 



BIBL. Ralfs, Ann. N. H. 1843, xi. 447. 

 xii. 104, 271, 346, 457; Thwaites, Ann. 

 N. H. 1847, xix. 200, xx. 9, 343 ; 1848, i. 

 161 ; Smith, Br. Diat. ; Bailey, Silliman's 

 Jn. xli.,xlii. ; id. Ann. N. H. 1851, viii. 157, 

 and Smithson. Contrib. 1854; Ehrenberg, 

 Inf.; id. Berl. Abh. 1839, 1840; id. Berl. 

 Ber. passim ; id. Mikrogeologie ; Brebisson, 

 Diatomees-, Kiitzing, Bac. and Sp. Algarum-, 

 Pritchard, Inf. (full account of species)-, 

 Braun, Verjung. (Ray Soc. 1853) ; Nageli, 

 Einzell. Alg. 9: Focke, Physiol Studien, 

 1853 ; Meneghini, SulV Animalit. &c. (Ray 

 Soc. 1853) ; Gregory, Diat. Clyde, 1857 ; 

 Smith (South France} Qu. M. Jn. 1855; 

 id. (Pyrenees}, 1857 ; Greville, Qu. M. Jn. 

 1859 (Californian), 1865 (Hong Kong), 

 1 ; H. L. Smith, Ann. N. H. 1869, iv. 218; 

 Grunow, Verh. zool.-bot. Gesellsch. Wien. 

 1858, '60, '62; Qu. M. J. 1877, 166 (Hon- 

 duras) ; Ny lander, Diat. Fennice fossil, addit. 

 1861; Weisse, Schwarz-Erde (Tscherno- 

 Sjom), 1855 ; Heiberg, Cotisp. Diat. danic. 

 1863 (6 pis.); Wenham, M. Mic. Jn. ii. 

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 Wallich, Mic. Tr. 1860, 129, viii. 36; 

 Ann. N. H. 1863, xi. 351 ; M. M. J. 1877, 

 xvii. 61 ; Schultze, Struct, d. Diat.-Schak, 

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