REPORT OF THE DIRECTOR I9IO 



213 



Development of brachials and sutural canals. The plates of 

 C. perforatus have something to tell of their own growth and 

 development. The greatest width of plate a, text figure 2, is 1.9 



Fig. 2 From a photomicrograph of a fragment of Cliocrinus perforatus xio. This 

 fragment is designated as the holotype of the spscies and is in the State Museum collection. 



mm and its primitive pair of b.vs., both above and below, 

 measured 0.43 mm from center to center at death. Plate e 

 has a width of but 1.4 mm, yet its primitive pair of b.vs. have 

 the same 0.43 mm between their centers. In the earlier 

 stages of plate a the distance between its primitive pairs of b.vs. 

 w^as no doubt but little if any less than at death. If w^e should out- 

 line the plate when it v/as about one fourth the diameter attained at 

 death we should find it possessed a median fold nearly as wide as 

 the plate itself and with but two b.vs. on each horizontal suture. 

 The addition of stereom to these sutures has carried the two pairs of 

 b.vs. directly away from each other and increased fourfold the ver- 

 tical distance separating them, yet one member of a pair has not 

 perceptibly increased its horizontal distance from its neighbor. 



If any horizontal suture should happen to lie in line or nearly in 

 line with another at the right or left, one primitive b.v. of a pair 

 would find itself in close proximity to one of the members of a 

 neighboring pair. These two unfortunatelv situated b.vs. would 



