— 2138 — 
Prorocentraceae. 
Exuviella Cienk. 
1. E. compressa (Bail.) Ostenfeld, Iagttagelser over Overfladevandets 
Temperatur, Saliholdighed og Plankton paa islandske og grenlandske Skibs- 
router, 1899, p.59; Dinopyxis compressa Stein, Der Organismus der In- 
fusionsthiere IIJ. Abtheil., Leipzig 1878—83, Pl. I, f.34—38. 
6 (rr). 
Area: Almost ubiquitous. 
Prorocentrum Ehrenbg. 
2. P. micans Ehrenbg. 
1q@r) — 2(rr) — 3(rr) — 6¢r) — S@r). 
Area: Atlantic, Mediterranean, Red Sea, Indian Ocean. 
Peridiniaceae. 
Pyrophacus Stein. 
3. P. horologium Stein l.c., Pl. XXIV, f. 1—13. 
1(rr) — 2@r) ~ 7Q@r) — 107). 
Area: Atlantic, Mediterranean, Red Sea, Indian Ocean, Pacific. 
Ceratium Schranck. 
4. (. tripos (O. F. Miiller) Nitsch. 
var. baltiea Schiitt, Pflanzenleben d. Hochsee, p. 266, f. 4a. 
I observed two slightly different 
forms both of which may be referred to | 
the above variety by Schtitt. The first 
form differs from Baltic specimens by 
the left posterior horn being somewhat 
bent forward. The second form observed 
is characterized by the posterior horns 
being longer and running more parallel. 
I name this form: 
f. parallela Schm. n. f. (see fig. 1). 
It closely approaches to the forms 
figured by Cleve in Report on the Phyto- 
Plankton collected on the expedition of 
H. M. S. ,Research*, 1896, Fifteenth 
Annual Report of the Fishery Board for 
Scotland, Part fll, Pl. 1, fig. 1, 1897. 
1 (rr) — 2Q7r) — 3(@tr) — 4Q9r) — 6(tr) 
8 (rr). Fig. 1. Ceratium tripos, var. baltica 
Area: Atlantic. Schiitt, f. parallela. Ventral view. 
