24 P. T. CLEVE, THE PLANKTON OF THE NORTH SEA, ENGLISH CHANNEL, ETC. 



Biddulphia aurita Lyngb. — Januan/: St Vaast r; Helder r; Väderö and Måseskär r. 

 Februari/: St Vaast r; Helder + ; W. of Schleswig c; at Skagen r; Måseskär and Väderö c. 

 March: St Vaast r; Helder cc r; Skagerak + r. April: Skagerak rr. December: Måseskär r. 



B. mobilensis Bail. — January: Plym. r; St Vaast +; Helder r; Väderö and Måse- 

 skär r. February: Plym. c; St Vaast c +; off the Dutch coast and W. of Danmark er; 

 round Scotland r. Marek: Plym.ce; S:t Vaast r; Helder r; N. of Scotland r. April, May: 

 Plym. c; Helder r; W. of Denmark r; Måseskär r; K. and \Y. of Scotland. September: 

 Helder r cc; Skagerak r. October: Skagerak r. November: Irish Sea +; W. of Denmark r + ; 

 Skagerak r. December: Plym. r; Väderö rr. 



Cerataulina Bergonii H. Per. — March: Helder cecr. April, May: Irish Sea r; 

 some points between Firth of Tay, S. Norway and the Skagerak r; Måseskär r; Helder c. 

 Jätte: Plym. r; Helder rr; Skagerak r. July: Plym. +; Måseskär r; Väderö rr. August: 

 Plym. +; Skagerak r. September: S. of Norway and Skagerak r. October: Skagerak + r. 

 November: off the Dutch coast r; SW. of Norway, Skagerak and Måseskär + r. 



Chaetoceros atlanticus Cl. — February: area between 58° N. 2° E.. 5G° N. 3° E. and 



Skagen r. Marek: N. of Scotland r; Skagerak rr. April, May: S. of Norway r; some 

 points in the central North Sea r. 



C. borealis Btw. — January: St Vaast rr; Väderö and Måseskär rr. February: 

 S. of Norway and Måseskärv. Marek: Måseskär r. April, May: 60°— 61° N. 1°— 2° E. r; 

 the North Sea between 58° and 54° N., not rare, most common in the central part; Måse- 

 skär r; Väderö r. June: Skagerak r. July: Gullmarfjord r. October: Väderö and Måse- 

 skär r. November: SW. of Norway r; Skagerak rr; Måseskär + . December: Väderö and 

 Måseskär + r. 



Var. Briglitwellii Cl. — February: 57° N. 5° E r; at Skagen and in the Skagerak r. 

 March: Måseskär r. April, May: GL°N. 1° E. r; 56° N. 1° E. r; 55° N. <;° E. r; Måse- 

 skär rr. June: Skagerak, Väderö and Måseskär r. July: Gullmarfjord r. October: Mase- 

 skär r. November, December: Skagerak + r. 



Chaetoceros constrictus Gran. — This aretie species occurred in September 1898 at 

 Vestmanna ö, in October the same vear at the Färöes. It was seen in 1899, April and 

 May, at the Färöes, in May at 61° N. 6° W. 



January: Måseskärv; February: S. of Norway r; Väderö and Måseskär + C. Marek: 

 whole Skagerak cc. April, May: 58° N. 4° E. +; 58° N. 7° E. cc; 57°— 58° N. 9°— 11 U E. c; 

 55° N. 6° E. r; Skagerak cc. June: Skagerak r. October, November: Skagerak +; Väderö er. 

 December: Väderö +. 



C. contortus Schött. — January, February: Väderö and Måseskär r. March: Skage- 

 rak c +; Väderö c +; Måseskär r. April, May: 58° N. 4°— 7° E.; 55°— 56° N. 6°-7°E. r; 



