KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 59. N:0 4. 19 



As I have mentioned above, I bave considered the specimen to be a young 

 one. Its very small size and the structure of the segments point to this, as well as 

 the small number of the arms and the absence of genital swollen pinnules. I have 

 already before touched on Minckert's opinion about the manner of the development 

 of the multibrachiate Crinoids. My opinion of the frequent occurrence of syzygies 

 in the above-mentioned four arms is that this is related to the fact that the arms 

 have not yet accomplished their ramification but will be exposed to a break with 

 accompanying duiplicative regeneration. The break of the arm would in such a case 

 take place between Br 1 and 2 or 3 and 4 and on the fracture so formed an axillary 

 would be regenerated with a couple of new arms, which would have the normal 

 distribution of syzygies by having one proximal syzygy less. Compare also the mode 

 of syzygial distribution in Zygometra microdiscus (St. 11) on an arm starting from a 

 II Br-axillary. 



Zy^oinetridrt} Clark. 



Zygometra Clark. 



Zygometra microdiscus (Bell). 



?Hyponome sursii 1808 S. Loven op. cit., p. 54. 



Antedon microdiscus 1S84 Bell »Alert» p. 103; 1888 1'. 11. Carpexter Chall. Rep., Vol. 26, p. 97: 

 1898 Döderleix op. cit., p. 47ii. 



Antedon multirudiata 1888 P. H. Caupenter Chall. Rep., Vol. 26, p. 94. 



Zygometra microdiscus 1907 A. II. Clark op. cit. 2, p. 348; 1909 op. cit. 16, p. 307: 1911 op, cit. 

 31, p. 458; op. cit. 32, p. 760; 1912 op. cit. 34, p. 103, op. 38, p. 11; 1913 op. cit. 40, p. 393: op. cit. 11. 

 p. 20; 1914 A. Reichensperger op. cit., p. 90; 1915 A. II. Clark op. cit. 42 and op. 43. p. 224. 



Zygometra multirudiata 1907 A. II. Clark op. cit. 2. p. 34S; 1911 op. cit. 32, p. 761; 1912 op. 34, 

 p. 104, — 



Zygometra microdiscus var. elegans (Bell). 



Antedon elegans 1884 Bell »Alert», p. 162; 1898 Döderlein op. cit., p. 475. 



Antedon fluduans 1888 P. H. Carrenter Chall. Rep.. Vol. 2<i. p. 94. 



Zygometra elegans 1907 A. II. Clark op. cit. 2, p. 348: 1909 op. cit. 16, p. 367; 1911 op. cit. 31 . 

 p. 458; op. cit. 32, p. 762; 1912 op. cit. 34, p. 104: 1913 op. cit. 40. p. 393; op. cit. 41, p. 21; 1915 op. 

 cit. 42 and op. cit. 43, p. 224. 



Localities: Zygo)netra microdiscus from St. 13 and var. elegans from St. 11. 



Description of the specimen from St. 13: Zygometra microdiscus. Cd flattened; the 

 dorsal pole bare, 3 mm in diameter. Cirri XLII in 3 to 4 irregular rows (only XVII 

 large C:i, the rest either being empty joint-cavites or in those regenerating young 

 C:i, XVI in number). The number of cirrals: 50 (dorsal knöt from 24 th ), 51 (dorsal 

 spine from 19 th ), 48 (21), 46 (19) juv., 48 (very young), 40 (16). The outgrown C:i 



