18 I\ T. CLEVE, NOTES ON SOME ATLANTIC rLANKTON-ORGANLSMS. 



Plialocroma minutum. N. Sp. 

 Plate VIII. Fig 10, 11. 



Longitudinal axis 0,or>, sagittal axis 0,04, transverse axis 0,025 millim. Areolation 

 coarse, 3 to 4 areoles in 0,oi millim. 



I have found this small form twice only, viz. at 41° N, 57° W. (July 1899) and at 

 41° N., 62° W. (August 1899). Temperature 22 to 24,4. Salinity 33,88 to 36,i3. 



Steiniella(?) punctata. N. Sp. 

 Plate VIII. Fig. 4. 



This species is characterized by its biconical form, solid membrane and coarse 

 areolation. Longitudinal axis 0,n, sagittal and transverse axis 0,06 millim. A nearly 

 related form has been described by Murray & Whitting (Träns. Linnean Soc. of London, 

 ser. 2, Bot., Vol. V, Pl. XXVI, fig. 4) as Ceratium biconicum, which also probably belongs 

 to tbe genus Steiniella. 



I have found this form once only in a sample from 48° N., 24° W. (August 1899). 

 Temperature 19,4. Salinity 35,63. Styli-plankton. 



IV. CYSTJE. 



Cysta limbata Cl. *) 

 Plate VIII. Fig. 15. 



By this name I propose to denote an organism, that has already been observed by 

 Hensen (»Welliger Statoblast» 5 tc Ber. d. Kieler kommission, Pl. IV, tig. 28, 29), but has 

 not got a name. It represents probably a stage in the development of some other orga- 

 nisms, perhaps some dinoflagellate, still, as it is of a certain importance to have a name 

 for it, I propose the above one. It is a cellule of nearly spherical shape, in diameter 

 about 0,05 millim., filled by a granular, probably green, mäss. The membrane is somewhat 

 thick and surrounded by a hyaline, plicate girdle, twice as broad as the enclosed cellule. 

 This form is not very rare in the northern Atlantic, the North Sea and the Skagerak. 



Hyalosphysa delicatula. N. Sp. 

 Plate VIII. Fig. 22. 



By this name I denote an unknown unicellular alga, which was found in samples 

 from the Azores (August 1898). It is remarkable for the very tliin membrane and small 

 scarce chromatophores scattered on • the inside of the wall. The form of the cellules is 



*) Since the aliove was written J0ROENSKN (Bergens Museums Aarbog 1899, p. 48) has nametl this 

 organism Pteroaphcera Möbii, which name has priority. 



