lO H. H. GRAN AND K. YENDO. M.-N. Kl. 



for determination with certainty. Re-examination of the specimen which 

 Yendo reported from Volcano Bay under C. WilleiY proved that the 

 plant belongs to the present species. 



Loc. Boshu Prov. (Okamura). Volcano Bay (Yendo). 



Chaetoceras Weissßogii Schutt. 



Schutt: 1895, P- 44» ^g- i/^, b. — Cleve: iSg-a, p. 22, 

 PI. 2, figs. 7 — 9. — Gran: 1906, p. jj, fig. 92. — Schröder: 

 1906, p. 335. 

 What Schröder mentioned under the present species in his paper, 

 1. c, has probably been identical with that reported by Okamura as 

 C teres Cleve. The two species are indeed hard to distinguish from 

 one another, except by the resting-spores. In some of our material we 

 have also doubtful specimens that may be referable to either. 

 Loc. Enoshima: Formosa Channel (Schröder). 



Sect. 5. Compressa Ostene. 

 Chaetoceras compressum Lauder. 



Lauder: 1864, PI. 8, fig. 6. — Cleve: 1873 b, p. 8. — Do.: 

 1894, p. 12, PI. 2, fig. 3. — Schutt: 1895, p. 43, fig. 16, a, b. — 

 Ostenfeld: 1902, p. 234, fig. 12. — Schröder: 1906, p. 336, 

 P- 350- — Okamura: 1907, p. 94, PI. 3, figs. 8 — 11. 

 = C. Kellen Brun (after Ostenfeld, 1. c). 

 = C. contortum Schutt: 1888, Taf. 3, fig. 4. — Do.: 1895, 

 p. 44. — Cleve: 1896 a, p. 6. — Gran: 1897 a, p. 14, PI. 2, 

 fig. 32. — Yendo: 1905, p. 46, fig. 7. — Gran: 1906, p. 78, 

 fig- 93- — Meunier: 1910, p. 22], PI. XXV, figs. 17 — 2-j. — 

 Yendo: 191 1, p. 26. 



== C. medium Schutt: 1895, p. 43, fig. 15. 

 The present species is characterised by having some of the setæ 

 in the middle of a chain enormously thickened. Schiøtt has etablished 

 the species C. contortum on account of the circular transverse section 

 of the frustules of European specimens, while in C. comjrressum it had 

 been reported to be complanated elliptical. 



After careful comparison of the specimens from various parts of the 

 Atlantic Ocean, the Japanese coast and the Bay of Bengal, Penang, etc., 

 we came to the conclusion that C. compressum Lauder, and C. contortum 

 Schutt are one and the same species. Moreover C. medium Schutt 

 has no marked difference to distinguish it from them. 



