2i8 DISCOVERY REPORTS 



to each segment. The rudiments of pinnules arise from the eleventh and succeeding 

 brachials. 



i6. Length of crown 3-5 mm.; length of column 11 mm. 



The column is similar to that of No. 15. There are 40 columnals and a damaged 



terminal plate. 



The crown is similar to that of No. 15. The radials are longer, being only slightly 

 shorter than the basals ; the dorsal surface of each is strongly rounded. The posterior 

 radials are in contact for more than half their length, beyond which they are cut away 

 to accommodate the proximal part of the radianal. The other radials are in complete 

 lateral contact. The radianal plate rests on the anal tube, completely covering it. There 

 is no naked perisome in the posterior interradius, and the orals of other interradii are 

 either in contact with the radials or separated from them by an extremely narrow strip 

 of perisome. 



17. Length of crown 5 mm. ; length of column 9 mm. 



There are 37 columnals and a large lobed terminal plate. The first columnal is short 

 and it bears the rudiment of a cirrus in each of the radii except the right posterior. The 

 remainder of the column resembles that of earlier stages ; each segment is encircled by 

 a faint but distinct median girdle. 



The crown is generally similar to, though smaller than, those of Nos. 15 and 16. The 

 radials, including the posterior pair, are in complete lateral contact. The dorsal surfaces 

 of the ossicles of the division series and of the brachials are strongly rounded. The arms 

 are of seventeen brachials of which the tenth and succeeding carry pinnules. 



18. Length of crown 5 mm. (Fig. 24/). 



The stem is of 40 columnals and a large lobed terminal plate. The first columnal is 

 short and it bears the rudiment of a cirrus in the anterior, the left anterior, and the left 

 posterior radii. The second columnal is as wide as the first and longer. The third to 

 fifth are narrower and discoidal. The remainder of the column resembles those of 

 younger stages. 



The basal plates are slightly longer than the radials. The radials are in complete 

 lateral contact. The radianal plate is far out of contact with the posterior radials, being 

 separated from them by naked perisome ; its proximal edge is opposite the distal end 

 of the costals. It is an oval plate resting on the anal tube which extends some way beyond 

 it_to opposite the end of the first brachial. The posterior oral plate is clearly visible 

 behind the anal tube. The proximal borders of the orals of other interradii are opposite 

 a point half way along the axillaries so that they are widely separated from the radials 

 by an area of perisome; a number of plates are present in it. The oral plates are of 

 coarse texture with their proximal surfaces pitted as in younger specimens. The distal 

 end of each narrows to a bar which bends in over the disk. 



The rays resemble those of No. 17. A few large sacculi occur at irregular intervals 

 along the arms. 



19. Length of crown 8 mm. ; length of column 13 mm. 



There are 41 columnals and a large terminal plate which is damaged. The first 



