ÖPVERSIGT AP K. VETENSK.-AKAD. FÖRHANDLINGAR 1900, n:0 8. 935 



Bhizosoleiiia styliformis Btw. Sparingly in inost saiuples 

 from 39° S, 10° W. to 43° S. 57° E., common to very common 

 from 43^ S. 71 E. to 36° S. 89° E. 



Synedra affliiis var. hybrida Grün. (Van IIeurck Syn. PI. 

 XLI f. 10). Rare specimens (0,06 m.m. in length, 0,00(J m.m. 

 in breadth, Striae 13 in 0,01 m.m.) were found at 44° S. 4' E.; 

 45 S. 11° E.; 45° S. 34° E. 



Synedra affinis is a litoral form, and such diatoms raay 

 drift a long way from the shore.s. Thus specimens of Achnan- 

 tlies longipes were found sparingly in most samples from the 

 Southern Atlantic and Indian ocean. Another example how far 

 such litoral forms can drift in the ocean is offered by the samples, 

 collected in October by the frigate "Tromp", from 49° N. 10° 

 W. to 40° N. 17° W. They contained Aulacodiscus argus and 

 some also Biddulphia gramilata. 



Thalassiosira antarctica Comber. (Ms. with photograph.) 

 The ordinary cellules are very thin-walled, 0,05 m.m., in dia- 

 meter, with a marginal row of close small apiculi, 6 in 0,01 

 m.m. The markings are delicate and arranged as in Coscino- 

 discus hyalirais Grun. (Fr. Jos. L. Diat. Pl. III f. 28) or as in 

 C. bioculahcs, about 17 in 0,01 m.m. The frustules are connec- 

 ted by a Single central thread. The endocysts are more silicious 

 than the ordinary cellules and coarsely areolated, areolse about 7 

 in 0,01 m.m., arranged in an irregulär fasciculate manner. The 

 margin has a row of close apiculi. There can scarcely be any 

 doubt about their identity with Coscinodiscus decipiens Grun. (A. 

 S. Atl. LIX f. 18, 19). Probably also C. antarcticus Grun. (Fr. 

 Jos. L. Diat. p. 84 Pl. C fig. 23) represents the same species. 



I found endocysts sparingly in samples from 42° — 43° S. 

 3° W.— 1° E.; 45° S. 26°— 34° E. 



Thalassiothrix longissima Cl. & Grun. More or less sparingly 

 in nearly all samples from 38° .S. 20° W. to 32° S. 91° E. 



This species variable as to the coarseness. The more from 

 the south the gatherings were, the coarser the frustules were, but, 

 on the other hand, they became very thin and narrow towards the 



