640 THE CRINOIDEA CAMEEATA OF NORTH AMERICA. 



which we infer the root was probably from four to five inches longer. The 

 branchlets are irregularly arranged; they were apparently quite long, as 

 one of them, which is preserved to the length of 3 cm., retains its full thick- 

 ness to the end. 



The number of arms probably varies from twenty-four to thirty to the 

 ray. The latter number occurs in two of our largest specimens, while 

 a smaller one in the M. C. Z., which Meek and Worthen identified as Stroto- 

 crinus ^lenwibrosus Hall, has but twenty-five. 



Strotocrinus glyptus Hall. 

 Pkde LX. Figs, la, b, c, and Plate LXV. Figs. 2a, h. 



I860. Aclinocrimts glyptus — Hall ; Suppl. Geo]. Kep. Iowa, p. 2. 



1881. Strotocrinus gli/pUis — W. and Sp. ; Revision Pateocr., Part IT., p. 160. 



A little smaller than the preceding species, the cup comparatively 

 shorter, and the tegmen convex instead of flat. Calyx obconical to the top 

 of the distichals, then bending abruptly outward and forming a decangular 

 rim at right angles to the axis of the calyx ; height to width at the rim as 

 two to three. Plates convex, covered with radiating ridges, meeting at 

 a small node in the centre, and communicating with the ridges from adjoin- 

 ing plates. Toward the basals there are four ridges from each antero-lateral 

 radial and the anal plate, and three from the anterior and two posterior 

 radials ; while there is but one between the other plates. Zigzag ridges, as 

 in S. regalis, formed by an angular longitudinal elevation on the brachials 

 in the rim, follow the lines of bifurcation, and leave angular depressions 

 between. 



Basal cup twice as wide as high, the sides almost vertical ; grooved 

 along the sutures ; axial canal moderately large and pentangular. Eadials 

 as wide as long, and nearly as large as both costals together. First costals 

 hexagonal, the second heptagonal, shorter than the first. The brachials 

 of the succeeding orders as long as wide, slightly decreasing in size up- 

 wards, each one supporting at one side an arm, of which the lower plates 

 are incorporated into the rim, at the other a brachial of higher rank, and 

 each arm giving off pinn^iles whose proximal joints also take part in the rim. 

 The arms proceeding from the distichals are free above the fifth plate, those 

 of the palmars from the fourth. There are eight bifurcations in this species, 

 giving origin to nine arms from the main branches, and eighteen from the 



