Report on tlie Echinoderms of North-East Gi'eenland. 245 



sely only in a pair of species, viz. Antedon rosacea (bifida) (by W. B. Car- 

 penter, Bury, S e e 1 i g e r a. o.) and Hathrometra Sarsii (by M. S a r s). 



The larvæ generally occur on the long marginal cirri, as shown 

 in PI. VIII, Fig. 3, but sometimes specimens were also found on the 

 inner, short cirri. Generally they were found on about the middle 

 of the cirrus, sometimes occurring two together. 



The youngest specimen is only 1'4 mm long, the stalk being 

 1 mm, the calyx 04 mm (PI. XI, Fig. 1). There are ca. 10 stalk-joints 

 (some of the lower ones could not be distinguished with certainty); 

 the middle ones are the longest, 015mm long, 005mm wide, with 

 the primary ring very distinct and somewhat prominent. The basal 

 disk simple, round. 



In another specimen of 25 mm length (the stalk 2 mm, the calyx 

 05 mm) the stalk has 15 joints; the three upper ones are quite 

 short, but not broader than those below; in the 4th joint the part 

 below the primary ring is somewhat elongated, the upper part still 

 remaining short. The following joints are elongated, quite cylindrical, 

 but with distinct primary ring; the longest joint is 025 mm long, 

 005 mm thick; the 3 — 4 lower ones are somewhat shorter. The 

 basal disk is small, slightly lobed. 



These two specimens, as well as several other specimens of 

 nearly the same size are all in the same stage of development 

 regarding the calyx, which I am designating as the stage I, in accor- 

 dance with Sars (as also the following stages are designated in 

 accordance with Sars), the calyx consisting onh' of the basalia and 

 the oralia, with no trace of the radialia (PI. IX, Fig. 1). 



The shape of the basalia is simply trapezoidal, with straight 

 edges, the upper edge being finely undulated, corresponding to the 

 lower edge of the oralia; the outer surface is slightly convex. They 

 afford a structural feature of some interest. As is seen in the figure 

 (PI. IX, Fig. 1) the lower part consists of an irregular meshwork, 

 while the upper part is quite regular in structure, the holes being 

 arranged in straight lines. This indicates that the lower part repre- 

 sents the plate in its original size, the regular upper part representing 

 additional growth ; that this is the correct explanation is evident from 

 the fact that the regular upper part becomes longer with age (Comp. 

 PI. IX, Figs. 1, 2 and 4). The same feature is observed on the oralia. 



The shape of the oralia is very characteristic. They are trian- 

 gular, with the side-edges and the apex turned outwards, so as to 

 be distinctly concave in the upper part (PI. IX, Fig. 1 ; PI. XI, Fig. 5, 

 see also the figures of the following stages). Along the lower edge 

 a narrow belt of regularly arranged holes, the growth-zone, has 

 appeared; it is distinctly smaller than that of the basalia 



