16 P. T. CLEVE, NOTES ON SOME ATLANTIC PLANKTON-ORGANISMS. 



Dinophysis Vanhöffenii Ostenf. *) 

 Plate VIII. Fig. 3. 



Under the name D. granulata I have described a small form (Kongl. Sv. Vet.-Akad. 

 Handl., Vol. XXXII, n:o 3, pag. 39, Pl. IV, lig. 7) from Spitzbergen, where it was found 

 among drift-ice. This form seems to me to be a small variety of a widely distributed 

 arctic species, named by Vanhöffen »D. ovata Clap & Lachm.» (Grönl. Exp. 1891 — 93. 

 Vol. II, 1 part, 1897, Pl. V, fig. 7). Ostenfeld (Iagttagelser över overfladvandets tem- 

 peratur, saltholdighet og plankton, 1898, pag. 58) proposed the name D. Vanhöffenii, 

 which I accept as it denotes the typical form, and my name a dwarf-form only. This 

 species, which seems to have been confounded with D. Miehaelis (Ehb.) Auriv. or D. 

 rotundata, is well characterized by its thick, coarsely areolated membrane, the upper part 

 of which scarcely proceeds beyond the girdle. The apical part has frequently some short 

 spines. 



I have seen this species in a collection from Jeddo Bay (Japan) and very frequently 

 in specimens from the northern Atlantic, between 81° and 52° N. Temperature 5,9, mean 

 of 21 obs., max. 9,8, min. — 0,9. Salinity 34,35, mean of 21 obs., max. 35,4i, min. 32,03. 



Peridinium diabolus. N. Sp. 

 Plate VII. Fig. 19, 20. 



This species has been figured by Murray and Whitting (Träns. Lin. Soc. of 

 London, 2 Ser. Bot., Vol. V, Part 9, Pl. XXIX, tig. 4 b) as a variety of P. divergens. 

 It is such a characteristic form that it merits to be considered as a species, remarkable 

 for its small size and the very strong posterior horns. I have found it in samples from 

 the Indian ocean and the Atlantic, where it has been observed from the region of Cape 

 Verde to the coasts of Portugal and near the Azores, besides S. of the Newfoundland 

 Banks and E. of Cape Hatteras. Temperature 14,8 to 24. Salinity 36 to 36,40. Belongs 

 to the styli-plankton. 



Peridinium elegans. N. Sp. 

 Plate VII. Fig. 15, IG. 



This species is nearly related to P. divergens and has been figured by Murray & 

 Whitting (Träns. Linn. Soc. of London, Ser. 2, Vol. V, part 9, Pl. XXIX, fig. 4 a) as a 

 variety of the named species. It differs from P. divergens by larger size (length 0,2, 

 breadth 0,i millim.), by the absence of teeth at the basis of the posterior horns and by 

 the ends of the girdle not being oblique. The longitudinal axis is slightly oblique to 

 the plane of the girdle. 



*) Dinophysis norvegica (CLAP. et Lachm.) JflRGENSEN (Bergens Museums Aarhog 1899, X. VI., Pl. I, 

 fig. 3 — (5) and 1). acuminata J0RO. /. c. fig. 7 — 9. 



