KONGL. SV. VET. AKADEMIENS HANDLINGAK. 



BAND 



32. 



n: 



o 8. 



21 



P. ovatuin PoLfCHET. — Rare in January o£f the Swedish west coast, in June W. of 

 Cape Stadt and in the E. Channel, in July in the Skagerak, in August at Plyraouth, 

 September to November at Helder. 



Pyrophacus horologium Stein. — In Mardi at 53° N. 4°E., in April very rare at 

 Plymouth, in June NW. of Hansthohn, in November S. of the Orkneys, ENE. of New- 

 castle (55°35'N. 0°34'E.) and at 56' N. 9°E. 



Pyrophacus horologium belongs to the tropical Atlantic (also the Indian Ocean) or 

 to the desmo- and styli-plankton, where it ' has considerably greater size than in the 

 North Sea, when among the tripos-plankton. 



FlagellataB. 



Phseocystis Pouchetii Lagerh. — At II el der very abundant in April and May, rare 

 in June, common in August and not rare in October. — At S:t Vaast la Hogue com- 

 mon in June, also in December. — ■ At Plymouth common from the beginning of April 

 to the beginning of June, rare in September. 



Cystae. 



Xaiithidiuiu Hystrix Cl. — Rare in the Skagerak in March, October and November. 



By the above name I denote an organism, which belongs to the tripos-plankton and 

 seems to be nearly akin to JL. brachiolatum Moebius, from which it differs by longer, 

 usually not divided, spines. Probably a stage in the development of some dinoflagellate. 



Fig. 5. Xanthidium liystrix Cl. 500 t. m. 



X. multispinosum Moebius. — In April at Måseskär, in June at Plyraouth, in July 

 at Måseskär, September, October in the Skagerak, alwa} s rare. 



