120 



E. Jørgensen. 



System of ring!;: On the whole hkc the preceding-, only the 

 ring-s are more irregular in shape and width. 



Outside the fourth ring- there seems to be traceable the be- 

 dnning of a 5th which is as yet not formed. 



Poi-ps : On the whole like those of the preceding. Very large 

 pores here and there on the edge of the disc, which would pro- 

 bably have formed several smaller ones later on. The byspines are 

 very scattered, fewer in number than in the preceding species, but 

 distributed over a larger part of the disc. 



liadial spines: The rings are united similarly to those in the 

 preceding species, but the number of radial spines around the disc 

 is larger, more than 30. The spines are narrower and more 

 irregularly developed, some being a little bent, turned outwards 

 and obhquely upwards, not all at the same level, equatorial, but 

 distributed over the broad, rounded margin of the disc. The length 

 of the spines is about the same as in the preceding species. 



Byspines: Very similar to those of the preceding species, but 

 more scattered and distributed over the whole of the disc nearly 

 out to the margin. 



Dimensions: The diameter of the inmost shell 12 ij., of the hrst 

 ring about 38, of the second 54, of the third 85, of the fourth 110. 

 Pores uneven, most of them being 2—4 ij-. The spines protrude as 

 much as to 30 [k The disc is 28 \>. in thickness. 



This form appears to ditfer considerably from the other spe- 

 cies on account of the irregularly placed marginal spines. The 

 specimen illustrated is probably not quite fully developed. 



Note. Sfyloiliefya aspera .TiiRH. (L. 91, p. (il) is a fourth 

 species. 



VII A. 4. Spongodifscida Hck. 



Spongodison»'! favns Ehrb. 



Ehbb. L. 53, p. 301. Hck. L. 86, p. 577. 



A species, which on the whole corresponds fairly well to the 

 description given by Haeckel of this species, was twice found to- 

 gether with Stylodidya tenuispina (cfr. under this heading). 



No inner rings w&tq seen. The disc was shaped like a 

 little thick, biconvex, lens. Towards tiie margin there were fine 

 radial spines here and there, some of these were a little protruding ; 

 but the disc did not appear here to be fully developed. The pores 

 towai'ds tlic mai'gin much larger than in the middle. Diameter 

 180 |).. 



Distribution: According to Haeckel, the North Atlantic, 

 Greenland, FaerOe Channel (Murray), surface. 



VII A. 



Irregular Spnmellaria. 



Tlie tliree foi-ms mentioned below of irregular Wpumellaria 

 are difficult to trace and explain, and have given mc a great deal 

 of work and taken a lot of time. Foi' each form I have briefly 

 mentioned the results I at last -arrived at; but there is still a good 

 deal of work left before a full light with regard to their structure 

 can be claimed. 



VII A. 5. Pjioiiida Hck. 



I'liorticiniu pyloninm (Hck.?) Cl. 

 (PI. X, f. 42, a-d: pi. XI, f. 4-2, e— f., f. 43—45). 



Cl. L. 30, p. 31, pi. 3, f. 2 a, b, c. Hck. L. SG, p. 709, 

 pi. 49, f. 10? Tetrapylonium Clerei Joeg. L. 91, p. 64. 



This species was first classed as Phorticium pyloninm Hck. 

 by Cleve, 1. c. Judging from his illustrations, the innermost shell 

 was not noticed, which would allow of the species being classed 

 as Phorticium pylonium, a form A\hich is probably little known. 



As I, however, found such an innermost shell, and apparently 

 3 systems of girdles, I concluded that I should refer the species 

 to the genus Tetrapylonium, as T. Clevei Joeo. n. nomen. Cleve 

 has, in a later work accepted this name and remarks that the spe- 

 cies is not identical to Phorticium pylonium Hck., probably because 

 he has also seen the innermost shell. 



After much fruitless labour, I at last succeeded — as far as I can 

 see — in getting a glear idea, in all important points, of the struc- 

 ture of this interesting species, and I have found it to be as described 

 below. As will be seen, it is quite different from that of the genus 

 Tetrapylonium and — as far as I can see — of all the others 

 mentioned by Haeckel. This would necessitate a new genus, if 

 there were not a possibility that the species is, after all, identical 

 to Haeckel's Phorticium pylonium. 



The genus Phorticium is too vaguely described by Haeckel 

 to be recognized, either after the desei'iption he gives or his illu- 

 stration. As, however, Haeckel speaks of P. pylonium as a very 

 frequent species of very varying appearance, there may be, as al- 

 ready suggested, a possibility of my species, after all, being found 

 to be the P. pylonium. 



The structure is principally as follows (cfr. pi. X, f. 42*): 

 On the most perfectly developed specimens there is on the very 

 outside a largest, lateral girdle, a broad oval or almost a rectangle 

 in shape, with rounded corners. (Cf. Cl. 1. c. fig. 2 a). Generally, 

 only the sides of this girdle, nearest to the transverse girdle, are 

 present. This outmost lateral girdle is seen in profile in a dorsal 

 view, looking perpendicularly towards its level (when the belt itself 

 it seen from the narrow side). Cleve's fig. 2 a gives such a dor- 

 sal view. 



Right in tlie middle of this girdle and placed perpendicularly 

 on it, dividing it into two equal parts, we find a second girdle de- 

 veloped where it must be shortest, namely, on a plane parallel to 

 the shortest side of the rectangle. This is the transverse girdle (the 

 designations correspond to Haeckel's). It is seen from the front 

 in the dorsal figure (pi. X, f. 42, a, b) and from above in the 

 apical one (pi. X, f. 42 c, d). In the lateral figui-e (pi. XI, f. 42, e, f) 

 the sidepieces of the girdle are seen from the front; they coincide 

 with the corresponding parts of the lateral girdle. 



Across this girdle a new one is similarly developed at the 

 shortest distance, perpendicular to both the former ones. This is 

 the sagittal girdle. It is seen in ])rolih' in the lateral figure (the 

 sagittal section) and from above right against its wide side on the 

 apical one (the transverse section). 



Again, perpendicular to this sagittal girdle and to the pre- 

 ceding one, and also where the distance is least, yet another girdle 

 is similarly developed, thus forming an inner lateral one parallel 

 to the outermost one. which is (lie largest. 



