1888.] NATURAL SCIENCES OF PHILADELPHIA. 377 



(PI. XX, rig. 21). The other ends emerge upon the ventral side, 

 where they present a considerable surface, containing a large ambu- 

 lacral groove. In order to attain this position, the plates, which are 

 wedge-shaped, bend inward and upward until their opposite ends 

 stand nearlv at right angles to each other, and the arms at their 

 origin pass out in a horizontal position. This can be seen in fig. 21 

 PL XIX, which represents a vertical section, giving a side view of 

 the same succession of plates as is shown dorsally by fig. 21, and 

 ventrally by fig. 21 on the same plate. The successive pieces are 

 numbered in each figure to correspond, and by comparing them, 

 and remembering that they present three different views of the same 

 elements, we think there will be no difficulty in understanding them. 

 We cannot see the least evidence of mobility of these plates until 

 they become free from the first radial, and thus attain the rank of 

 arm plates. Whenever the arms are found folded up, the bending 

 from a horizontal to a vertical position takes place in the lower 

 arm plates, and not in the higher radials. The lanceolate areas, 

 which are such a conspicuous feature of the ventral surface, and 

 extend from the second axillary to the fifth or sixth bifurcations, 

 are formed by a great thickening along the outer edges of the 

 marginal plates of two adjacent rays, and therefore consist of two 

 rows of arm plates, respectively radials, decreasing in width in their 

 upward arrangement. 



The anus is excentric, and in C. pulcher takes the form of a large 

 tube, while in all authentic specimens of C. rugosus it seems to be a 

 simple opening. The form and position of the tube have been 

 wrongly described by us. Angelin's beautiful looking figure, pur- 

 porting to show it to its full length (Icon. Crin. Suec, PI. XVII, 

 fig. 1), originating at the edge of the calyx, and lying outside the 

 arms, proves to be an ideal figure, based upon the erroneous inter- 

 pretation of some fragmentary pieces. Our specimen (PL XX, fig. 

 11) shows the base of the tube very well, but not its full length. To 

 judge from the fragments, shown by Angelin's PL XXV, figs. 8 — 

 13, it must have been of considerable length in some specimens. It 

 seems to have been somewhat more highly organized than the anal 

 tube of the Camarata generally, and to approach the ventral sac of 

 the Fistulata. The actual length has not been observed, but from 

 the manner in which the large cavity within tapers in different speci- 

 mens, we have no doubt that the opening is at the upper end, and 



