Some Chaetoceras and Peragallia 

 of Japan. 



Plate III-IY. 



By 

 K. Okamura, Rigakiihakushi. 



Genus I. Chaetoceras Ehb. 



Subgen. I. Phaeoceras Gran. 



Section 1. Atlanticse Ostf. 



1. C. atlanticum Cleve. PL IV, Figs. 56-63. 

 Cleve Arctic Sea, 1873 a, p. 11, PL II, Fig. 8 a, h ; Gran., 



Diat., 1905, p. 64, Fig. 74.— C. dispar Castr., 1886, Report, 

 p. 76, t. 8, f. 6. — C. compactum Schutt, Chast. und Perag., 1895, 

 p. 46, f. 23. 



Loc. in Jap. : Pro v. Tosa ; 40 miles off Shinshirijima (Kurile : 

 Lat. 46 D 10' N ; Long. 151° 40' E). 



Among our specimens represented in PL IV. Figs. 56—63, 

 there are some such as those figured in Figs. 59 and 61—62, which 

 resemble in the forms of the cells very much like C. skeleton ; 

 but the direction of spines are different from that of those of the 

 latter species. — Only I am not sure whether the specimen shown 

 in Fig. 63 is the present species or C. neapolitanum Schrod. 



The specimens figured measure as follows : in Figs. 56 and 

 61, breadth = 17 and 35//, length = 10 and 7.5 ,u, height of 

 foramen 11 and 12 ,«, length of horn-root 5 and 7.5 ft, respec- 

 tively ; in Fig. 57, breadth and length = 10 and 20//; in Fig. 

 58, breadth = 22.5-24/z ; in Fig. 60, thickness = 15 u. 



Section 2. Boreales Ostf. 



2. C. densum Cleve. PL III, Figs. 16-17. 

 Cleve Season Distr., 1901. p. 299 ; Gran., Diat., 1905, p. 67, 



Fig. 79. — C boreale v. Brightwelli Cleve, Arctic sea, 1873 a, t. 



