LONG-HORNED DIATOMACEiE. 107 



the cup-shaped and hispid character of our Breydon species, 

 but is destitute of the neck. Syndendrium diadema and Di- 

 cladia capreolus are common species ; they are found with the 

 other Clicetoceri, in various eartlis, and guano, and appear to be 

 of the same family. They are chiefly distinguished by long 

 styles, proceeding from the rounded end of the frustule, which 

 styles are branched at the end, and are not unfrequently found 

 with a portion of the membrane adhering to them, in which 

 they seem to have been imbedded. Omphalotlieca hisjnda has 

 the appearance of an imperfect frustule, and Mastogonia prcB- 

 texta, of a semi-frustule of Goniothecium Roger sii. 



We venture to give a synopsis of the CJicetoceri, adapted to 

 our present imperfect state of knowledge of these singular 

 organisms. 



CHiETOCEROS. 



Filamentous ; filaments elliptical, fragile, imperfectly siliceous. Frus- 

 tules without strife, united in pairs by the interlacing on each side, of 

 horns proceeding from the frustules, or from a cingulum between the 

 frustules. Horns often of great length, and sometimes spinous, or 

 serrated. 



^ Horns, four on each side. 



1. 0. Tetracheta, Ehrenb., Kutz., spec. Alg. 138. 



§§ Horns, tivo on each side, and proceeding from tubular apertures 

 in the frustules. 



* Horns filiform. 



2. C. Dichoeta, Ehrenb., Kutz., spec. Alg. 138. 



3. G. Didymus, Ehrenb., Kutz., spec. Alg. 138. 



4. C. f Bacillaria, Bailey, Kutz., spec. Alg. 138. 



5. C.i Bipiloneiis, Bailey, Kutz., spec. Alg. 138. 



6. G. Gastridium, Goniothecium Gastridium, Ehrenb., Kutz., spec. 



Alg. 23. See Plate VIL, figs. 3—8. 

 N. B. — To Ehrenberg's description should be added, " Cornubus 

 utrinque duobus." This species clearly belongs to the genus 

 Ghcetoceros. Many examples have occurred with the horns 

 perfect. See Plate vii., fig. 



7. C. incurvum, Bailey. Smithsonian Contributions, Feb. 1854, p. 9. 



Plate VII., figs. 9—11. 

 We have found this species abundant in guano. 

 Mr. Tuffen West has detected in guano frustules of a species, belonging 

 to this section, which is new to me, and may perhaps be C. Bacillaria, 

 Bailey. For figures of these frustules see Plate VIL, figs. 1, 2. 



** Horns spinous, or serrated. 



8. C. horeale, Bailey. Smithsonian Contributions, Feb. 1854, p. 8. 



Plate VIL, figs. 12—15. 



9. C. Peruvianum, Brightwell. Frustules hemispherical. Horns pro- 



ceeding from the centre of the circular end ; very stout 

 and long, and beset with short spines, recurved. 



* I am also able to state, that C. Wighamii and Goniothecium his- 

 pidum have lately been gathered in the bay of the Isle of Roa, near 

 Ulverstonc. 



