Report on tlie Echinodernis at North-East Greenland. 251 



single specimen of a Pentacrinoid of Antedon petasus (Düb. Kor.), 

 the only Crinoid occurring there. 1 take the occasion to describe 

 and figure here this Pentacrinoid which was hitherto unknown 

 (Pl.X, Fig.3). 



The specimen is in a stage which corresponds to the 4th and 

 5th stages of Sars, both the first pinnulæ and cirri having appeared 

 contemporaneously, while in H. Sarsii the pinnulæ appear before 

 the cirri. The calyx, with the arms, measures 2 mm, the stalk 

 ca. 4 mm. The calyx does not seem to show features of value as 

 specific characters. ' There is no trace of infrabasalia. The oralia 

 are of the usual concave shape, still in connection with the radialia I. 

 The anal plate is still distinct. The first pinnulæ are attached to the 

 11th — 12th arm-joint. The cirri are radial in position. The stalk con- 

 sists of 27 joints, the 9 upper ones being quite short, and the two 

 uppermost ones conspicuously broader than the rest. The fully formed 

 joints (PI. XII, Fig. 8) are hourglass-shaped, widened at the ends in the 

 usual way, the long axis of the joint-surfaces alternating at right angles. 

 There is no trace of the primary ring in these joints; they are 

 rather short, only 03mm long, by 01 mm wide. Towards the lower 

 end of the stalk the joints become gradually shorter, as seen in the 

 figure. The basal disk is only slightly lobed. — The specimen was 

 fovmd attached to a Balanus on a shell of Pecten maximus. 



When reviewing the diff"erent species of Pentacrinoids here treated 

 one feels rather convinced that characters by which to distinguish 

 the different species are not to be found in the calyx. The fact that 

 pinnulae and cirri appear contemporaneously in A. petasiis (this is 

 also the case in the species treated by W. B. Carpenter), while 

 in H. Sarsii the pinnulæ appear before the cirri, is certainly very 

 conspicuous but it is, in any case, not of use for distinguishing the 

 other stages (more probably this indicates a generic distinction). 

 The more or less distinct widening of the upper stalk-joints would 

 also appear to afford a character for specific distinction; it seems, 

 however, not to be quite constant, and judging from the figures 

 given by Sars, it is only on the appearance of the cirri that they 

 begin to widen, while before this stage they are not distinctly wider 

 than the rest of the joints. It is unfortunate that no specimens of 

 the Pentacrinoids of H. prolixa have reached this stage, so it cannot 

 be ascertained whether this holds good also for this species, but it 

 is probable that it will prove to do so. Only the fully formed 



^ The calyx certainly ajjpears somewhat лу1Нег than in the other specimens. 

 This, however, depends on the fact that the specimen has been slightly compressed 

 in the preparation, which fact also accounts for the small naked spaces seen at 

 the upper end of the basal ia. 



