1886.] NATURAL SCIENCES OF PHILADELPHIA. 203 



the truncated side of the basal disk. The articular facet for the 

 attachment of the column has a lateral position, and is placed 

 within the centre of the two equal pieces, without touching at 

 an}^ point the third plate. It is large, somewhat excavated, and 

 divided vertically by the suture line. 



The radials consist of four plates of very irregular arrangement. 

 The two larger ones, those of the lateral rays, occupy more than 

 two-thirds of the anterior side of the calyx, and support two small 

 transverse brachials, of which the upper one is axillary. Two 

 much smaller and very irregular plates, which are generally sepa- 

 rated by the large lateral pieces, form the radial of the anterior 

 ray. The large lateral radials are bent abruptly along their outer 

 sides, so as to occupy considerable space upon the posterior side 

 of the calyx. They are hexagonal rarely pentagonal angular 

 at their upper and lower ends ; one of the lower sloping sides 

 abuts against the first anterior radial, the other against the basal 

 disk. The sloping upper face connects at one side with the second 

 anterior radial, the opposite side supports the first brachial plate. 

 Of the lateral faces one meets the corresponding side of the 

 opposite radial, the other an anal plate. In the anterior ray, the 

 first radial is linear, but more frequently triangular, two of its 

 sides resting within a re-entering angle formed by the lateral 

 radials. The lower edge is generally wider, and constitutes the 

 bottom part of the anterior face of the calyx, being on a level 

 with the truncated edge of the basals, and united with them by 

 muscular articulation. The articulating surface, near the outer 

 margin of the component plates, is provided with a deep fossa, 

 evidentl}^ for the lodgment of elastic ligament. A similar but 

 narrower fossa is placed close to the inner margin of the plates, 

 separated from the former by a narrow transverse ridge. The 

 middle part of this ridge extends somewhat into the large fossa, 

 and forms a kind of triangular projection which contains a small 

 axial canal. The second anterior radial has nearly the same form 

 as the first, but its position is reversed, the truncate side being 

 directed upwards, the angle downwards, resting between the 

 sloping upper sides of the adjoining basals. In Calceocrinus 

 chrysalis, in which the first anterior radial joins the second, both 

 plates are exceptionally quadrangular, and, therefore, the first 

 lateral radials pentagonal instead of hexagonal. The plates 

 above are free. There are two brachials in each lateral ray, a 



