lis 



The pores on the outside shell vaiy considerably in size and 

 shape, both on one and the same individual and on different ones. 

 They range from quite tiny, circular shaped, to large, longish holes. 



Also the width of the intermediate walls between the pores 

 i> very variable; on the other hand, then- thickness is never great. 



The shell next to the outside one is always strong, thick-wal- 

 led, with very uneven pores, roundish and oblong, most of them 

 being 10 — 16 |j., although sometimes considerably smaller or larger. 



The ball next to the inside one answers in all important re- 

 spects to the corresponding one in Echinomma leptodermitm. 



The inmost shell is difficult to see. Its diameter is abouth 16 \k 

 I have not succeeded in getting it out uninjured when breaking 

 the outer balls, so that I cannot give a good drawing of it. 



Cleve's Actinomma borealis is undoubtedly the same as this 

 species. He seems, however, to go too far in his opinion of the 

 variations in the radiolaria, as will be seen on reference to his 

 illustrations fig.s a and b (1. c, pi. 1, f. .5 a and 5 b). He looks 

 upon them as young forms of the same species which he illustrates 

 in tig. 5 c. I think that f . 5 b = Echinomma lejitodermvm, f . 5 a 

 is probably the same species (too few main spines depicted on the 

 illustration?) without a developed outer shell. 



Rather frequent, both on the north , and west coast, though 

 rai-ely at all somewhat numerous. As is the case with the other 

 SpimieJIaria with us only found in deep water. 



Distrihiition: The same as that of Echhiovima leptodcniuou. 

 Found by Cleve in deep water samples from the sea west and 

 south of Spitzbergen (L. 30, p. 26). Also known from a few pla- 

 ces in the North Ocean as well as (efr. Cleve L. 40, p. 136) a 

 couple on the American side of the Atlantic, near the surface. 



Rhizoitleg'iiia boreale (Cl.) JOrg. 

 (Pl. IX. f. 38, pl. X. f. 38 e— f.). 



Hcxadorua hvrealis Cl. L. 30, p. 30, pl. 2, f. i, a, b, c. 



Rhizoplegvia boreale (Cl.) Jorg. L. 91, p. 61. 



Easily recognized by the characteristic interwoven pyramids 

 around the main spines (pi. IX, f. 38 b). 



Haeckel depicts similar pyramids for Rhizople(jina hjchiiospha-ra 

 (L 86, pi. 11, f. 5). 



The inside shell is irregular, not quite round; sometimes re- 

 sembling a cube in shape, sometimes it is more hke an octahedron. 

 The pores ai'e uneven, irregular, polygonal, averaging about 10 [a. 



The intermediate walls between the pores are not broad, differ- 

 ently developed, but never having the distinct broader corners which 

 correspond to the rounded lumen of the pore. A few small, short, 

 needle-shaped byspines are found hei-e and theic on the beams, 

 but not regularly in the corners. 



The main spines are long and strong, often 8 in number (ac- 

 cording to Haeckel's system answering to an inner cube), although 

 also often only 6 (answering to an octahedron) or 7. A larger 

 number may sometimes be found (cfr. pi. X, f. 38, c— f.) The 

 main spines have 3 strongly developed edges wiiich luu■l■o^^• off too- 

 wai'ds both ends. On these edges there are transverse branches 

 diverging at right angles and these, together with the correspond- 

 ing ones on the othei- edges of the same spine, form a very vari- 

 able number of verticils of threes. 



The spongy, loose and very irregularly consti'ucted network, 

 which forms the outer shell, arises from the lowest 2 — 3 verticils 

 on the main spines, but has the appearance of being lengthened 



out a good way up along the radial spines, on account of the 

 thin connecting beams, which unite the different verticils parallel 

 to the direction of the spine (fig. 38, a, b). 



Also on the outside of the outer spongy .shell (network), there 

 are some few scattered short and fine, needle-shaped byspines. 



The ocean forms seem generally to have 6 radial spines. 



There seems to be a slight difference between the regular foi'ms 

 which have 6 radial spines, and those which are more frequently 

 found in the coast water and which have about 8. The former seem 

 to have a smaller inner shell with distinct byspines. I have, how- 

 ever, not discovered any definite difference so as to make it necessary 

 to divide them into two or more species. 



Young forms (cfr. pi. X, f. 38, e — f. and Cl. 1. c. pi. 2. f. 

 4 a) are rather unrecognizable, as both the interwoven pyramids 

 and the spongy outer shell are absent. 



The construction of this species i-esembles greatly that of 

 Mhizoplecpna radicatum Hck. and JR. lijclinosphæra Hck. The inner, 

 fine, transverse branches on the radial spines in the space between 

 the outer, spongy shell and the inner shell are, however, wanting. 

 These transverse branches are by Haeckel the characteristic of 

 the subgenus Rhizoplegmklium. 



According to Haeckel's system, it might perhaps be a ques- 

 tion as to whether or not our species should be classed as belonging 

 to the genus Lychnosphæra, because of the byspines on the inner 

 shell. As these, however, are small and few in number, and per- 

 haps not even always present, this would not be recommendable, 

 and still more so as such a distinction between the genera seems 

 to be unnatural. 



Haeckel's genus Hexadoyas has radial spines without side 

 branches, for which reason I still mean that the above species finds 

 a more natural place among the closely allied foi'ms of the genus 

 Rhizoplecpna, notwithstanding that there undoubtedly often occur 

 forms with 6 main spines. 



Belongs to the most common radiolaria with us and is not rare 

 in deep water samples, although never numerous. 



Distribution: On the west coast of Norway rather fre(|uent, 

 although rare in fully developed condition. Known from the sea 

 west and south of Spitzbergen (Cl. L. 30, p. 30) and from a feu- 

 places in the Norwegian Ocean. 



VII A. 3. Porodiscida Hck. 

 St^'lodirtya Ehrh.. Hck. 



iSpecics of this genus seem only to occur (juite exceptionally 

 with us. I have only seen a very few individuals, which appeal', 

 however, to belong to species hitherto unknown. All have more 

 or less distinct circular, inner rings, not spiral-shaped, and belong. 

 therefore, to Haeckel's subgenus StyJodictyon. 



In deciding a species, it is of great importance to examine the 

 shaj)e of the disc in side view. 



I have only included in my list those species in which 1 am 

 acquainted with this shape. 



S. tenuispina Joro. n. sp. 

 (PI. X, f. 39). 



Shape of the slnU in side view: ^\lmost linear, though some- 

 what thicker in tlic middle and slightly narrowed towards the ends 



