XI. Balanocrinus. 393 



in those that are swollen or ridged, but is more marked in 

 lobate or stellate examples [cf. d^Archiac's fig. 16 a). At 

 first one observes a simple alternation in height, in E 22019 

 the heights are 2*5 mm. & 20 mm., mean diameter 6'7 mm.; 

 then an increase in the diameter of the higher ossicles, thus 

 in E 21961 the measurements are 2 mm. & 7'3 mm., and 

 1*7 mai. & 7*0 mm., respectively ; finally, colamnals of 3 or 

 more, perhaps 4, orders, distinguished by both height and 

 diameter (E 21964). In quinquelobate fragments the larger 

 projecting columnals are not so depressed radially as are 

 the smaller ones, and this produces a somewhat scalariform 

 surface *(E 21964). 



The Number of Columnals in an internode, as observed 

 in the dozen intersyzygia available, varies from 15 to 32. 

 The material is too limited to permit of satisfactory con- 

 clusions being drawn, but the following facts may be noted. 

 The highest columnals occur in the internodes with only 15 : 

 in E 21981 the height is 2-55 mm., in E 22027 it alter- 

 nates from 3*2 to 2'5 mm. The lowest columnals are in the 

 internode with 32 (E 21983), where they are in three orders, 

 from 1'7 to 0'8 mm. This last has a stellate section and 

 certainly comes from a more proximal region of the stem. 

 Three orders are also manifest in the specimen with the 

 next number of internodals, viz., 31 (E 20982), but the 

 height of the ossicles is rather greater, 2*6 to 1*5 mm. The 

 two fifteeners are plane and quite smooth (E 22027) or with 

 a slight ridge of sparse granules (E 21981). Those with 

 the higher numbers have more or less swollen and ridged 

 ossicles as a rule. E 21975 is exceptional in that, though 

 ridged, it is plane and has equal internodals of 2*5 mm. in 

 height. On the whole, the facts suggest that the height of 

 the internodals was greater in the distal region, but that 

 the whorls were at more frequent intervals. This applies 

 only to full-grown individuals. While height of columnals 

 and the extent of their alternation in size must depend 

 mainly on position in the stem, it appears that ridging and 

 swelling have not that connection — at all events, in so great 

 a degree, — but are characters of the individual. Stellation 

 or marked lobation were probably most common in young 

 stages and in the proximal region of adult stems ; the facts 

 are consistent with that view, but there was certainly some 

 individual variation as between circular, pentagonal, and 

 slightly lobate. 



The Radial Pore lies at the bottom of a depression, which 

 is well marked in some specimens, generally smooth ones 



