1886.] NATURAL SCIENCES OF PHILADELPHTA. 199 



In this special names were given to parts of the calyx, which, as 

 we will presently show, are represented in other genera, and hence 

 should be designated by the same name, the more since some of 

 his appellations conflict seriously with terms long ago established. 

 Hall divided the calj-x into two parts. The one, which he called 

 the " dorsal side," comprises the anterior side and not, as should 

 be expected from the name, the aboral part ; the other, which he 

 designated as the " ventral side," by which are usually under- 

 stood the oral or summit portions, represents the posterior 

 side. According to Hall, the " dorsal side " consists of three 

 perhaps sometimes five " basals," of the " upper and lower dor- 

 sal plate " or the first and second anterior radials, and of the 

 right and left " dorso-lateral plate " or lateral radials. He further 

 discriminates between " plates of the dorsal arm," the brachials 

 of the anterior ray, and those of the " dorso-lateral arms," or arm 

 plates of the lateral rays. The " ventral " side is described as 

 being composed of the "ventral arching plate" which actually 

 consists of two pieces, and which either are anal plates, or non- 

 arm-bearing radials and succeeding these of a row of plates, 

 longitudinally arranged, which were designated as "plates of the 

 ventral side," but which are plates of an anal tube. There are 

 besides summit or vault pieces which, however, were not described 

 by Hall. 



The most remarkable feature of this genus is represented by 

 the basals, which are located on the posterior side of the calyx. 

 They connect with the plates of the anterior side, which is trun- 

 cated, toward the basals, not b}^ suture as in the case of other 

 Crinoids but by muscles and ligament, thus producing between 

 basals and radials a marked articulation. There is a widely gap- 

 ing suture along the articular line, which, as Meek and Worthen 

 suggested, permitted the basals to be opened out on a line with 

 the radials and other parts of the calyx. That the calyx was 

 capable of bending at this point is well shown by a unique speci- 

 men of Galceocrinus tunicatus Hall, in the possession of Mr. 

 James Love of Burlington, in which the main body stands out 

 from the column at an angle of sixty degrees ; while in most of 

 the specimens which we have examined the crinoid hangs down- 

 ward, almost parallel with the column. No specimen, however, 

 shows the calyx in an erect position. 



There are in this genus but three rays, which vary considerably 



