936 P. T. CLEVE, S. ATLANTIC PLANKTON. 



north. There were found in my saniples both the very coarse 

 form, collected in the antarctic regions by the Challenger Expe- 

 dition, and finer forms quite similar to those of the Arctic Ocean. 



Tropidoneis antarctica (Grun.) Cl. {Ämphiprora (?) ant. 

 Grun. — Navicula Challencferi Grün. — Stauroneis glacialis 

 Castr. Chall. Rep. Diät. PI. XXVII f. 11) was found sparingly 

 in almost all samples from 42° S. 3° W. to 43° S. 57° E. 



The plankton, collected during December 1899 and January 

 1900 in the South Atlantic and the South Indian ocean, has the 

 characteristics of a mixture of styli- and tricho -plankton in 

 variable relative quantities. Although it is at present scarcely 

 possible to classify all the noted forms in the one or other type, 

 at least not in a conclusive manner, still, I will try to arrange 

 them in the plankton-types, to which they belong with the 

 greatest degree of probability. 



I. Styliplankton-forms. 



A, Occurring also in the teraperate or boreal Atlantic of 

 the northern hemisphere: 



Anij)horella amphora. Ceratium bucephalum. 



A. Steenstrupn. C. fusus. 



Codonella pusilla. C. Uneatum. 



Dictyocysta elegans. C. 77iacroceros. 



D. mitra. C. tripos. 



D. templwn. Dinophysis liomunculus. 



Tintinnus lusus undce. Diplopsalis lenticula. 



Undella caudata. Gymnaster pentasterias. 



U. Claparedii. Oxytoxum scolopax. 



Glohigerina. Peridinimn diaholus. 



Dichtyocha fibula. P. Michaelis. 



Distephanus speculum. P. oceanicum. 



Halosphoera. R. pedunculatum. 



Ceratiwin arietinuni. Chcetoceros (atlanticus v.) exi- 

 C. azoricum. - guus. 



