112 



There is already a considerable accumulation of names (and 

 correspondiug- confusion?) in connection -with this form, which -will 

 be difficult to keep separate from the foregoing, as it, as mentioned 

 in a previous paper (J(')kgensen L. 91, p. 42), varies consider- 

 ably. 



I cannot help discussing here once more, whether the names 

 above mentioned are justifiable, as the last change of name will 

 easily give rise to a state of chronic confusion. 



I believe everyone except perhaps Ostenfeld, agrees that 

 Schutt's name ought not to be used. Even if the illustration re- 

 ferred to by Ostenfeld be taken as the principal figure (Schutt 

 L. 130, p. 70, f. .35, IV), it must not be overlooked that Schlttt 

 has in the same work at another place (p. 28, f. 20, IV c) illu- 

 strated the foregoing species as v. scotica. It was this circumstance 

 which made me decide to keep my own name instead of the one 

 already published by Ostenfeld. 



Also Cleve (L. 40, p. 301) and Bruno Schr()der (L. 129, 

 p. 15) look upon Schutt's var. scotica as I do. 



There must either be a printer's mistake in one or other of 

 iSchutt's two illustrations, or the name scotica must be used in 

 reference to a large series of forms. 



In L. 112, p. 56, Ostenfeld enters Cerat. tripos r. horrida 

 Cl. as a form under C. t. v. ,.scotica Schijtt". He remarks that 

 its straight (not curved) apical horn brings it close to this variety, 

 and that the presence or absence of spines is a very varying and 

 unreliable character. 



With this latter remark, I agree entirely (cfr. L. 91, p. 42 

 under C. t. m. f. intermedia). Judging from my experience, it seems 

 that car. horrida Cl. can hardly be kept distinct as a variety, and 

 it will be seen (L. 40, p. 227) that Cleve too has come to the 

 same conclusion. But Ostenfeld's reference to the straight apical 

 horn, must arise from some mistake (which I confess I find it 

 difficult to explain), as Clevf's figure (L. 46, f. 4) clearly shows 

 the curved horn which is typical for C. loiujipes Bail. (= C. t. r. 

 ti'i-gestina Schutt, cfr. under C. longipes). 



All the forms illustrated by Ostenfeld, L. 110, p. 585, f. 

 136 — 139, belong to my C intermedium, as was my earlier inter- 

 pretation of this form as a variety (1. c. where the forms are of 

 (Mjual value to the varieties in this paper, and the varieties equal 

 to the species here). C. intermedium in the tables is also taken 

 in this meaning, and includes all Ostenfeld's forms. 



Strange enough, the same mistake is also repeated by Gran 

 (L. 70, p. 195) matters being brought to a head by the use of 

 tiie name C. horridum for the whole series of forms. 



Cleve (L. 40, p. 225), on tlie contrary, enters rar. horrida 

 under C', t. var. longipes Bail. 



Is the series in question to be considered as one species — 

 which, as mentioned above, will perhaps not be realisable — I 

 cannot see but tliat the name C. intermedium must be resumed. 



Clevh (L. 10, p. 225) evidently considers the forms in ques- 

 tion to I)elong under C. maeroceros (in agreement with my previous 

 opinion). 



On the whole, very frequent, almost precisely coiTcsponding 

 in fre([uency to C. marroceros, tliough sometimes a little scarcer. 



Very scarce during the sprini 

 in 1899. 



Distribution: Appears in 

 same as that of C', mucrucerus. 



diatom inflow, altogether absent 



all important respects to be the 

 In the Norwegian Ocean, however, 



not noticed (by me, at any rate) so far north. Frequent on the 

 west coast of Norway. 



C. longipes (Bail.) Cl. 



C', tripos c. tergestiiia Schutt. Incl. C. tripos r. horrida Cl., 

 non C', horridum Gean. 



As mentioned in an earlier work (L. 91, p. 43) Bailey's 

 Peridinium longipes seems to answer best to Cleve's C. tripos v. 

 horrida. This variety is quite typical in the Arctic Sea, but at 

 lower latitudes appears to pass entirely into C. tripos v. tergestina^ 

 From this cu-cumstance, I cannot either see any reason why Bai- 

 ley's name for the whole series of forms should not be used as 

 in fact it now is by almost all authors on plankton. 



This form also varies so much that it will be difficult to limit 

 it. Cleve still enters it in L. 40, p. 225 as C. t. var. longipes. 



Very frequent, often in large numbers, more frequent than 

 C. maeroceros and intermedium, about the same as C. tripos; in 

 February — March and during the diatom inflow more frequent than 

 the latter species. Also found by Gran, rather numerous, in the 

 months of July — October 1898 — 99 at several places on the north 

 coast. 



Distribution: Northern temperate form, which is especially 

 found in the coldest part of the northern Atlantic and in the con- 

 fines towards the arctic waters, as well as in the north eastern 

 arms, the North Sea (frequent in the English Channel in Feb. 

 1903, less so in May), Skagerack, Cattegat and the Baltic. Fre- 

 quent between Greenland, Iceland, the Faeroe Islands, Scotland 

 and the coast of Norway to Spitzbergen (cfr. Cl. L. 40, p. 225) 

 and Jan Mayen. In these northern waters the form horrida Cl. 

 appears to be most frequent. Common on the ^\•est coast of Nor- 

 way, especially in the spring months after the diatom inflow (April — 

 June 1898). 



C. arcticiiui (Ehrb.) Cl. 



Very rare, only found in two samples: 



Strommen II, (Henningsvær) ''/2 1899, 0—30 m., r; Sea ott' 

 Rost (Vesteraalen) "h 1899, +• 



Distribution: Arctic species, ncritic and oceanic, especially 

 frequent at Spitzbergen and Greenland and in the boundaries be- 

 tween the arctic and Atlantic waters (cfr. Gran L. 70, p. 50 — 52 

 and L. 69, p. 10). 



Occurs in the sea between Norway and .Ian ^layen, but only 

 occasionally comes near the coast, mostly in deep water. Accord- 

 ing to L. 18, IV singly in the North Sea and ott' Scotland, May 

 1903. Absent round the Faeroe Islands. It is also wanting on 

 the west coast of Norway (only on one occasion observed ott the 

 north western coast, as far down as the Sond Fiord. 



C. fiirca (Eiinn.) Dim. 



Very frequent, usually rather numerous (the frequency varies 

 considerably from r to c), nmch scarcer during the spring diatom 

 inflow. Found frequently at several places on the iioi-th coast in 

 the months of July— October 1898—99 by Gkan. 



Distribution: Temperate oceanic form, extending from the 



warmer part of the Atlantic, the North Sea, Skagerack, Cattegat, 



the Baltic, the west coast of Norway, Scotland, Iceland to the 



most northern part, (not in the ai'ctic waters). Common on the 



I west coast of Norway, often in quantities in late autumn. Rather 



