20 P. T. CLEVE. THE FLANKTON OF THE NORTH SEA, THE ENGLISH CHANNEL, AND THE SKAGERAK. 



C. tripos var. longipes Bail. — A. The North Sea. March: more or less scattered 

 över the chceto region, from Scothind to Norwa^y, Skagen and the W. of the Danish Pen- 

 insula. June: abundant W. of the Hebrides, E." of Firth of Tay (56°30'N. 0°38'E.) and 

 at 55° 25' N. 0"^ 8' E., less abundant W. of Skagen aitd above the Fisher Bank. July, 

 August: sparinglv W. of- the Danish Peninsula (observations incomplete). November: 

 almost absent from the North Sea, but common at Helder in November and December. — 

 B. In the E. Channel: at Plymouth rare in March, April, not rare in June, July and in 

 December. — C. In the Skagerak: as a rule rare from January to June and from 

 September to the end of the year. 



C. tripos T. bxicepliala Cl. A. In the North Sea: rare in March on some spöts 

 (at 57° N. 6°E., 56° N. 1°E. and 55° N. 1°E.), not seen in June and August. In No- 

 ver)iber not rare, sometimes common, round Scotland and between Scotland, Norway and 

 Skagen, rare at 53° N. 4° E. and 55° N. 5° 30' E. — In the Skagerak rare in January 

 and from August to December. 



C. platycorne v. Daday (— C. trip. v. aurita Cl.). — Very rare in November at 

 Plymouth (drifted from the region of the Azores). 



Dinophysis acuta Ehrb. — In the North Sea as a rule rare, in March and June 

 at some spöts in the eastern region, in November at several points between Newcastle 

 and Skagen. In the Skagerak rare from January to March, in June and July and from 

 October to the end of the year. 



Diplopsalis lenticula Bergh. — In June rare N. of Holland, in November E. of 

 Scotland. At Plymouth rare from January to August. In the Skagerak rare in July and 

 in October. 



Gonyaiilax spinifera Clap. & Lachm. — Rare in March in the North Sea (at 

 56° N. 0° and 55° N. 1° W.). In the Skagerak common in January, not rare in No- 

 vember, December. 



Peridiiiiiiiu depressum Bail. — A. In the North Sea more or less rare in June in 

 the eastern part, common NW.^of Heligoland and W. of Skagen. In July, August, more or 

 less common N. of Holland and on the Fisher Bank. In November more or less rare at 

 several points bet\veen the N. of Scotland, S. Norway and Skagen. In the Skagerak 

 more or less rare from Januai-y to June, less rare in October, December. 



P. divergenslEHB. — In the North Sea as a rule rare among the tripos-plankton. 

 In the Skagerak rare in January, less rare from July to October. 



P. Michaelis Ehb. — Rare in April at Plymouth, in June W. of Schleswig, in 

 October at Måseskär. 



P. oblongum Auuiv. (= P. diverg. v. obl. Aur. and P. div. v. oceanica Vanh. Ostenf.). 

 Rare in June in the E. Chaiinel at S:t Vaast, in July ut Helder, in the Skagerak and at Måseskär. 



