RONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:0 2. 1.59 



Gissocrinus elegans. 



(Plate VIII, tio-s. 284—292.) 

 1878 Angelin, Iconographia, p. 10, Tal). III, figs. 5, 5 d. 



Diagnosis. 



Dorsal Cup a rather broad cone; its plates with axial ridges. IBR low. BB greatest 

 width rather greater than height. HR wider than high, with facet a little more than 

 halt' width. IBr 1. IIBr 2; laterally apposed. Arms branch about 7 times, rather short. 

 Arm-ossicles wider than high, with curved sutures; expand slightly distalwards and have 

 a slight distal ridge; slightly compressed laterally. Patelloid plates may be present. 

 Ventral sac vertieal; distally composed of parallel series of almost quadrangular plates, 

 lying side by side. with regular transverse folding. Stem-ossicles circular, low, of equal 

 height, but alternately ridged; lumen small. 



This species was founded on a single specimen of a crown with one or two stem- 

 ossicles attached (a). In this specimen the cup is crushed, the plates ont of position and 

 partlv broken, so that the original shape of the cup cannot be made out exactly, but it 

 certainly was a broader cone than in Tab. III, fig. 5. There is also a specimen (b) from 

 the quarry between Bara and Wallstena, a finely grown individual. 



It is somewhat difficult to separate this species from G. typus, especially as specimen 

 b is even nearer to that species than is a. The only differences that can be laid hold of 

 are the presence of two secundibrachs, the breadth of the arm-ossicles and the curved 

 sutures between them. I retain the species provisionally. 



Description. 



Dorsal Cup a rather broad cone, the absolute measurements of which cannot be 

 distinguished in the specimens owing to crushing in a and matrix in b. The plates are 

 strong] y ornamented after the fashion of G. typus and G. eampanula. Height in a about 

 9 mm. 



IBB 3; the sutures cannot be seen because of the ornament. Height in a 3 mm. 



BB 5; hexagonal or pentagonal; post. B truncate above. Measurements in a: height 

 § mm. or 4.75 mm., width below 4 min., width above 5.75 mm. or 5.5 mm. 



RR 5. Measurements in a: height to bottom of facet 4 mm., width below 6 mm., 

 width above 8 mm., height of side 5.75 mm., breadth of facet about 4.75 mm. 



Arms: in <t traced to VIBr, in b to VIIBr or VIIIBr. In a the length is about 27 

 mm., but it is probable that they are not all preserved: in b they are much longer in propor- 

 tion to the cup. The brachials as seen from the back are wider than high throughout (fig. 

 286); they expand slightly distalwards and have a slight ridge at the distal end; the pro- 

 portion of the dorso-ventral axis is much the same as in G. typus (fig. 287). The su- 

 tures between the ossicles are curved. The axial canal is distinct (tig. 289). In the 

 proxiinnl series, the brachials of adjacent arms are closely apposed, and in this respect 

 the species resembles G. eampanula (fig. 291). In the general trend of the arms, how- 



