H. H. GRAN AND K. YENDO. 



M.-N. Kl. 



= C. boréale var, Brightuelli Cleve. 1873 b, p. 12, fig. 7 a, 

 (non. b — e). Do. 1897 a, p. 20, t. i, fig. 2. 

 Loc. Tateyma (Okamuna); Misaki (Yendo). 



Subgen. II. Hyalochaete Gran. 



Sect. 



Dicladia Grak. 



Chaetoceras decipiens Cleve. 



Cleve: 1873a, p. 11, fig. 5. — Gran: 1897a, p. 13, PI. 1, 

 figs. 2, 3; PI. 3. figs. 3, 4. — Do.: 1904, p. 535, PI. 17. figs. 

 I — 6. — Do,: 1906, p. 74, fig. 88. — Schröder: 1906, p. 337. — 

 Meunier: p. 219, PI. XXV, figs, 12-16; PI. XXVII, figs. 4, 5, 

 PI. XXVIII, fig. I. — Ostenfeld: 1910, p. 274, fig. 9. — 

 Pavillard: 191 i, p. 22, fig. i A. 



= C. decipiens f. concreta Gru- 

 Now: Cleve et Grunow: 1880, 

 p. 120. 



= C. concretum Engl, i 883, p. 1 1. 

 The seasonal variation in the form 

 of the frustules of this species has been 

 already noted by Gran in Nordisches 

 Plankton, p. 75, and in Depths of the 

 Ocean p. 319. The same condition is 

 also found in the material from the 

 Pacific Ocean. In the specimens from 

 southern Japan, the foramen is generally 

 more rounded than in those from north- 

 ern Japan. 



In the specimens from Volcano 

 Bay both the terminal horns and the 

 lateral setae are clearly punctated, the 

 younger and more delicate setae excep- 

 ted. On the other hand, in some chains 

 such markings are entirely lacking. 

 Hence the presence or absence of the 

 punctuation on the horns or setae must 

 not be regarded as a distinction be- 



Fig. 3. Chaetoceras decipiens Cleve. tween this species and C. LorewHa»l(W. 



a. Terminal portion of a broader This may remore the doubt which 



chain. X 360, „ ,, 



b. A portion of a narrow chain. Ostenfeld (1. c. p. 274) entertams, 



X 520. about the point in question. The angles 



