PLANKTON OK THE JAPANESE COAST. 



133 



Height of body of the specimen figured measures ca. 0.09 mm. ; 

 breadth, ca. 0.08 mm. 



Loc. in Japan : Prov. Tosa ; Shinoshima in Prov. Owari. 

 Other known loc. : Atlantic Ocean ; Red Sea. 

 33. P. tumidum Sp. nov. (Pl. V., fig. 37). 



This species, which is characterised by the swollen body and by the 

 possession of a list stretched between the bases of antapical horns, is so 

 nearly related to Peridinium elegans that one might consider it simply a 

 variety of the latter species ; but there exist differences in the shape and 

 size of body, in the absence of teeth at the bases of antapical horns and in 

 the almost horizontal girdle. In P. elegans, as known to me (fig. 38, a. 1.), 

 the list stretching between the bases of antapical horns is visible, but not 

 so manifestly as in the present species. 



Loc. in Japan : Prov. Tosa. 

 34- P- elegans Cleve. (Pl. V., fig. 38). 



Cleve, 1900 a, p. 16; Pl. VII., figs. 15, 16. — Murr, and Whitt, 1899, 

 Pl. XXIX., f. 4 a. 



Cleve gives in his Atlantic Plankton Organisms, Pl. VII., fig. 16, a 

 side view of this species, in which figure the body is represented so thick 

 that the thickness much exceeds the breadth ; perhaps this may be a 

 misrepresentation. 



The specimen figured measures : height of body taken from the apex 

 of apical horn to the tooth at the base of an antapical horn, 0.09 mm. ; 

 breadth of body, 0.083 mm - ; thickness, 0.045 mm. 

 Loc. in Japan : Prov. Tosa. 



Other known loc. : Atlantic and Indian Oceans ; Red Sea. 

 35. P. diabolus Cleve. (Pl. V., fig. 39). 



Cleve, 1900 a, p. 16; Pl. VII., fig. 20.— Murr, and Whitt, 1899, PI. 



XXIX, f. 4 b. 

 Ostf. and Schm., 1 901, p. 174. 



Length of apical horn in the specimen figured measures ca. 0.037 

 mm. ; that of one of the antapical horns, 0.037 mm > height of body, 

 0.09 mm. ; breadth of same, 0.11 mm. 



