KONGL. SV. VET. AKADEMIENS HANDLINGAR. HAND 34. N:o I. 21 



the an gles, ;ill turned in an angle of 15° — 20° towards the longitudinal ;i\is, thinner 

 and stronger intermingled. Terminal awns very long, stronger than the others, angular, 

 with spirally arranged small spines, wnich bucorae stronger towards the distal end. 

 Kndocysts in the iniddle of the céllulés, biconvex, covercd with numerous, long bristles. 



Longitudinal axis 0,or_> to 0,028. Sagittal axis 0,02 to 0,02. r >. Lndocysts 0,009 to 0,oi2 

 long. Their sagittal axis 0,02 to 0,025 milliin. This species was found in March 1898 at 

 7°N., 55° W. (Temperature 25,9.) 



This species is well distinguished from all known forms by the absence of foramina, 

 by the direction of the awns by the endocysts and the si/e. In the absence of foramina 

 and the direction of the awns it reminds of the very small form, which I havc named 

 C. subtilis (Bih. till. Kongl. Sv. Vet.-Akad. Handl., Vol. XXIII 3, n:o 5, fig. 8). Another 

 form without foramina I found in plankton from the Caspian Sea. 



Chretoceros Ostenfeldii. N. Sp. 

 Plate VIII. Fig. 19. 



Chains flexible, with large oval foramina, as large as the cellules. Céllulés thin- 

 vvalled, with concave valves, somewhat longer than broad. Awns thread-like, short. 

 Terminal setae stronger than the others. Cell-contents (as far as could be ascertained on 

 alcohol-preserved specimens) with one chromatophore along the wall of the zone. 



Longitudinal axis of the cellules 0,oi. Sagittal axis 0,007 millim. 



This form has a considerable resemblance to C. laciniosus Schutt, but is much 

 more delicate and has a single chromatophore. It has been distinguished by Ostenfeld 

 (Iagttagelser över overfladsvandets temperatur, saltholdighed og plankton, in 1898) as 

 »C. laciniosus of.» 



It was observed in April 1898 abundantly at 49°— 48° N., 19°— 29° W., rarer in 

 the Irminger Sea and the Färöe Channel, but became there eonimon in May. Låter it 

 was seen only rarely, but in August it was found abundantly between Iceland and 

 Greenland. 



Dactyliosolen hyalinus. N. Sp. 

 Plato VIII. Fig. 33. 



Cellules cylindrieal, L' 2 to 2 times longer than broad, firmly united into confervoid 

 threads. Valves circular flat, without any visible structure and with simple, not crenulate 

 margins. Zone with numerous transverse rings, 2 in 0,oi millim., not distinctly punctate. 

 Chromatophores small. Length of the cellules 0,06 to 0,08, their diameter 0,04 millim. 



This species was found from February to June 1898 in the region of the New- 

 foundland Banks, associated with species belonging to styli-plankton. It reappeared on 

 the same area in November. Temperature 14,4, mean of 32 obs., max. 20, min 8. Sali- 

 nity 35, mean of 27 obs., max. 36,49, min. 32,62. 



